If I don't turn the central air on in the morning, when the attic is cooler, the air handler won't come on but the compressor outside fires up. At night when the attic cools down, the air handler will work. I have replaced the T-Stat but that didn't help. Today, I put the fan on first, and it came on. I then hit the cool button and the compressor outside came on and all is fine. Previously, with the fan on auto, I hit the cool button and the compressor outside came on but no blower in the attic. Is there something in the air handler that senses heat?

My first guess is to take a look at the capacitor on your blower motor. If this goes bad, your motor may not start reliably.
The ambient temperature may affect the characteristics of the capacitor enough to allow the motor to start when conditions are favorable.

There is, unfortunately, no good way to test capacitors besides swapping in a known good one.

This post (https://www.askmehelpdesk.com/heating-air-conditioning/bryant-plus-90-blower-runs-intermittently-179635.html) shows one success story.

Good luck,
WallyH

My first guess is to take a look at the capacitor on your blower motor. If this goes bad, your motor may not start reliably.
The ambient temperature may affect the characteristics of the capacitor enough to allow the motor to start when conditions are favorable.

There is, unfortunately, no good way to test capacitors besides swapping in a known good one.

This post (https://www.askmehelpdesk.com/heating-air-conditioning/bryant-plus-90-blower-runs-intermittently-179635.html) shows one success story.

Good luck,
WallyH


Thanks WallyH - I know what the capacitor looks like on the outside compressor unit (I watched a tech replace it a few years ago) Will the capacitor look similar on the blower unit? I'm handy enough that I would attempt to replace myself.

Thanks WallyH - I know what the capacitor looks like on the outside compressor unit (I watched a tech replace it a few years ago) Will the capacitor look similar on the blower unit? I'm handy enough that I would attempt to replace myself.
Yes, it will be very similar. Usually it is mounted to the blower assembly itself. Hopefully, what you'll find is it is swollen or something obvious.

Make sure you get an exact replacement (although you can get one with a higher voltage rating if you have to). Also, there is the possibility of voltage still present on the capacitor even with the power removed, so use insulated needle-nose pliers to pull the wires off the terminals.

Let me know how it goes.
WallyH

Yes, it will be very similar. Usually it is mounted to the blower assembly itself. Hopefully, what you'll find is it is swollen or something obvious.

Make sure you get an exact replacement (although you can get one with a higher voltage rating if you have to). Also, there is the possibility of voltage still present on the capacitor even with the power removed, so use insulated needle-nose pliers to pull the wires off the terminals.

Let me know how it goes.
WallyH

Wally - Thanks for the heads up on the capacitor. I got shocked a few years back from a capacitor. I didn't get badly hurt but it scared the you know what out of me. It melted the tip of my screw driver to a screw.

What's odd about this situation is once the air handler starts blowing air, its good until I turn it off. For instance it started today as I had mentioned after I put the fan to "on" instead of "auto" and then clicked the cool button. It's been running fine all day. Even after it hits it's target tempature, it will clycle on and off (if it was on auto of course)although the attice is blazing. It's after it's been off for a while that the trouble starts with the heat in the attice and the blower not going on.

That is odd behavior. And I've been known to come up with theories to explain something to fit in with a pre-conceived notion, so it is not a certainty that the cap is the problem. I happened to have extras lying around, so it was easy for me to swap in a different cap to test with. I know that most people don't have this luxury.

Best of luck,
WallyH

That is odd behavior. And I've been known to come up with theories to explain something to fit in with a pre-conceived notion, so it is not a certainty that the cap is the problem. I happened to have extras lying around, so it was easy for me to swap in a different cap to test with. I know that most people don't have this luxury.

Best of luck,
WallyH

Well all was going well with running the air with the fan set to the "on" position then a few minutes ago, the blower cut out but the compressor outside kept running. I'm going to venture up there after this 100 degree weather stops to see what's what. Is there an access panel of sorts that will house the capacitor and other connections like the T-stat wires from the hall way?

Well all was going well with running the air with the fan set to the "on" position then a few minutes ago, the blower cut out but the compressor outside kept running. I'm going to venture up there after this 100 degree weather stops to see whats what. Is there an access panel of sorts that will house the capacitor and other connections like the T-stat wires from the hall way?

So after the fan kicked off, I clicked the switch to auto, left the fan off for 10 minutes
And clicked the fan back to the on position and now its working.. weird.

Two things. First you can check if a capacitor is good if you have a voltage meter that has capacitance. It is signified as UF or a line with an arrow in it. Turn the power off to the air handler. Then discharge the capacitor (short the two terminals with insulated pliers or a screwdriver). Then remove one lead and read the two terminals. It should read at least 7.5 but the rating is on the side of the capacitor.

THE bigger question is does the air handler have a float switch in the drip pan. If the pan is full it will kill your ac, but it shuts the whole system down including the outside condenser so that system will not be able to remove any more humidity.

There is a panel usually on the side to access tstat wires, blower motor, and capacitor usually mounted on the blower motor. But shut it down (power), usually controlled by a lightswitch or disconnect, and open the panel nearest where your wires run in.

Two things. First you can check if a capacitor is good if you have a voltage meter that has capacitance. It is signified as UF or a line with an arrow in it. Turn the power off to the air handler. Then discharge the capacitor (short the two terminals with insulated pliers or a screwdriver). Then remove one lead and read the two terminals. It should read at least 7.5 but the rating is on the side of the capacitor.

THE bigger question is does the air handler have a float switch in the drip pan. If the pan is full it will kill your ac, but it shuts the whole system down including the outside condenser so that system will not be able to remove any more humidity.

There is a panel usually on the side to access tstat wires, blower motor, and capacitor usually mounted on the blower motor. But shut it down (power), usually controlled by a lightswitch or disconnect, and open the panel nearest where your wires run in.

Leddfoot - There is a drip pan under the unit but it's not used. The system is set up with a pipe that runs from the unit to the outside about 20 feet of pipe. It looks to be about 5/8 cooper pipe. The condensation then drips to the outside. The problem is always with the blower in the attic, never the condenser outside however. I do have a sperry meter that measure voltage and ohms. I'll try testing the voltage. So far tonight, the fan in the attic cut out 3 times while the condenser outside kept running. After setting the cool setting to off, and waiting about 10 minutes, I turn the fan back on and click on the cool button and everything works. So far its been running fine on the "auto" fan setting which yesterday it wouldn't come on unless it was set to "on"... weird.

Ok the drip pan under the unit if it seems unused and you are running ac then it is a backup pan and there will be one inside under the evaporator coil where the copper pipes run into the air handler. Check for a float there although again, usually a full float pan will kill the call to the outside condenser. The copper pipe is actually the freon lines to that run to the outside condenser. Also (with the power off) in your air handler, try to spin the blower fins on your evaporator fin. A last note, the evaporator fan is typically but not always controlled by the green lead of your thermostat. You can check the call if you clip on the common side (meter on voltage) of the low voltage and find where the green lead returns to the air handler from the thermostat. However, note, this is a "hot check", don't do if uncomfortable with voltage, and if your air handler may have a door switch that kills all power when you open it.

Leddfoot - There is a drip pan under the unit but it's not used. The system is set up with a pipe that runs from the unit to the outside about 20 feet of pipe. It looks to be about 5/8 cooper pipe. The condensation then drips to the outside. The problem is always with the blower in the attic, never the condenser outside however. I do have a sperry meter that measure voltage and ohms. I'll try testing the voltage. So far tonight, the fan in the attic cut out 3 times while the condenser outside kept running. After setting the cool setting to off, and waiting about 10 minutes, I turn the fan back on and click on the cool button and everything works. So far its been running fine on the "auto" fan setting which yesterday it wouldn't come on unless it was set to "on"... weird.
If the fan cuts out while running, I'd be less inclined to suspect the capacitor (but it could still be a problem--there are motor run capacitors). Also, measuring the voltage won't tell you much. Capacitance is a hard thing to measure (which is why the best test is swapping in a good cap). I suppose if the blower is getting really hot, it may cut out for thermal reasons (there is a thermal cutout).

All furnaces are a little different, but there should be a panel that you can remove to expose the blower. If you're lucky, it will be set up to slide straight out, revealing the motor and capacitor, etc. Or, even better, have the capacitor right out in the open like this (http://www.masterplumber.net/images/HPIM1455.JPG).

Best of luck,
WallyH

Once again, capacitance is easily tested if your meter has capacitance. Turn power off, make sure power is off, dischage capacitor with insulated pliers or screwdriver (short terminals to each other and to ground(case)). It should typically read greater than 7.5 uf but the exact rating should be printed on the side. Of course, you have to have a meter that read capacitance and it is simple. Capacitance is the symbol to the right of the ohm symbol at this link. Fluke 187/189 Digital/Analog Multimeter (http://us.fluke.com/usen/products/features.htm?cs_id=26864(FlukeProducts)&category=HMA(FlukeProducts)). A capacitor diminishes as it fails and when it reaches the edge it gets intermittent.

Once again, capacitance is easily tested if your meter has capacitance. Turn power off, make sure power is off, dischage capacitor with insulated pliers or screwdriver (short terminals to each other and to ground(case)). It should typically read greater than 7.5 uf but the exact rating should be printed on the side. Of course, you have to have a meter that read capacitance and it is simple. Capacitance is the symbol to the right of the ohm symbol at this link. Fluke 187/189 Digital/Analog Multimeter (http://us.fluke.com/usen/products/features.htm?cs_id=26864(FlukeProducts)&category=HMA(FlukeProducts)). A capacitor diminishes as it fails and when it reaches the edge it gets intermittent.
I do agree that it is easy enough to measure capacitance if you have the right equipment.
However, I think the normal homeowner/handyman in general does not have a meter that can measure capacitance. These are more specialized items that are not as common.

WallyH

Ok the drip pan under the unit if it seems unused and you are running ac then it is a backup pan and there will be one inside under the evaporator coil where the copper pipes run into the air handler. Check for a float there although again, usually a full float pan will kill the call to the outside condenser. The copper pipe is actually the freon lines to that run to the outside condenser. Also (with the power off) in your air handler, try to spin the blower fins on your evaporator fin. A last note, the evaporator fan is typically but not always controlled by the green lead of your thermostat. You can check the call if you clip on the common side (meter on voltage) of the low voltage and find where the green lead returns to the air handler from the thermostat. However, note, this is a "hot check", don't do if uncomfortable with voltage, and if your air handler may have a door switch that kills all power when you open it.

Leddfoot - Actually the cooper pipe does lead to the outside as a drainage. There are also the freon lines coming in from the outside condenser. As a side note, I have base board heat. The central air unit isn't at all involved with the furnace. I have the outside compressor and the air handler... a rather massive looking unit is suspended from the joist's in the attic. So far today it was running fine and about 5 minutes ago... around the hottest time of the day, the blower kicked out again and this time isn't going back on... so says my wife.

If the fan cuts out while running, I'd be less inclined to suspect the capacitor (but it could still be a problem--there are motor run capacitors). Also, measuring the voltage won't tell you much. Capacitance is a hard thing to measure (which is why the best test is swapping in a good cap). I suppose if the blower is getting really hot, it may cut out for thermal reasons (there is a thermal cutout).

All furnaces are a little different, but there should be a panel that you can remove to expose the blower. If you're lucky, it will be set up to slide straight out, revealing the motor and capacitor, etc. Or, even better, have the capacitor right out in the open like this (http://www.masterplumber.net/images/HPIM1455.JPG).

Best of luck,
WallyH

Wally - I have baseboard heat. The furnace isn't involved with the central air unit. I have a compressor outside (York) and the air handler is in the attic suspended from the joists. It's a huge brown box with the ducts running out of it. Is there a thermal sensor in this type of air handler in the attic? If so, that would seem to me to be the obvious issue.

Wally - I have baseboard heat. The furnance isn't involved with the central air unit. I have a compressor outside (York) and the air handler is in the attic suspended from the joists. It's a huge brown box with the ducts running out of it. Is there a thermal sensor in this type of air handler in the attic? If so, that would seem to me to be the obvious issue.

So it appears what ever the problem is has become permanent. The air handler fan cut out today around 4:30 and it's not going back on at all. We're expecting some strong storms tonight and relief from the 100 degree tempature luckily. I'm going to go up in the attic this weekend and remove the run capacitor to get a replacement. I'll let you know if that works.

Wally - I have baseboard heat. The furnance isn't involved with the central air unit. I have a compressor outside (York) and the air handler is in the attic suspended from the joists. It's a huge brown box with the ducts running out of it. Is there a thermal sensor in this type of air handler in the attic? If so, that would seem to me to be the obvious issue.
I'm not familiar with this type of unit, but I would think that any modern motor would have a thermal cutout either on it, or close to it. If it is external, it should be in line with the power wires to the motor.

Good luck up there!
WallyH

Wally Helps sounds as if he has hit the nail on the head> Seems to me the "internal" overload is tripping off inside the evap motor. The cause could be the cap. Or dirty blower wheel that helps cool the motor's windings,

The motor and capactor both should be replaced now because the overload is so week or burned and the overload is inside of the motor be sure to put in a new cap. Of the right MFD and voltage

I know this is a fairly big job, it shoud be done by an A/C tech. To avoid this problem in the future change filter more often if the blower wheel is real dirty.

I'm not familiar with this type of unit, but I would think that any modern motor would have a thermal cutout either on it, or close to it. If it is external, it should be in line with the power wires to the motor.

Good luck up there!
WallyH

I appreciate your help. I learned/learning allot on this site. So I did some testing these last 2 days after the heat wave. Here's the deal. This has been going on for 2 years now. If we didn't turn the central air on in the morning, we would have to wait until the attic fan cooled the attic enough at night, then the blower would come on. For the last 2 days, if I turn the blower on in the morning when the attic is cool, the blower goes on no problem. If I try turning the blower on around 5:00 PM or so, it doesn't go on. So definitely there's something in the blower that senses it's too hot in the attic and doesn't allow the blower to turn on. I believe that I was told about the run capacitor in the blower, is there a start capacitor as well in this blower? I haven't gone up there yet to look in the blower.

There is such a thing as a start and a run capacitor, but I would bet that you'll have one or the other. If you have both, they'll most likely be in a single package with 3 leads.

Good luck,
WallyH

There is such a thing as a start and a run capacitor, but I would bet that you'll have one or the other. If you have both, they'll most likely be in a single package with 3 leads.

Good luck,
WallyH

Hi Wally - I just got around to replacing the capacitor yesterday morning. Initially I thought that solved the problem because when I came down from the attic, the blower came on.. Of cource it was the morning, and the attic hadn't heated up yet. 1 hour later I tried the blower but it didn't come on. Interestingly enough, when I went back up to the attic; I think it's a relay or transformer (the wires from the T-stat and other wires connected to it and it was 3-4 inches to the right of the capacitor) was really hot, abnormally hot. Above this relay/transformer was a smaller circuit board looking devise with a few wires connected to it also. Any way, I have that relay/transformer out and will replace it. I'll keep you posted.

Hi Wally - I just got around to replacing the capacitor yesterday morning. Initially I thought that solved the problem because when I came down from the attic, the blower came on.. Of cource it was the morning, and the attic hadn't heated up yet. 1 hour later I tried the blower but it didn't come on. Interestingly enough, when I went back up to the attic; I think its a relay or transformer (the wires from the T-stat and other wires connected to it and it was 3-4 inches to the right of the capacitor) was really hot, abnormally hot. Above this relay/transformer was a smaller circuit board looking devise with a few wires connected to it also. Any way, I have that relay/transformer out and will replace it. I'll keep you posted.
I'm still really interested in how this turns out! Good luck.

I'm still really interested in how this turns out! Good luck.

I'll definitely let you know. As I look at what I've recently removed, I'm thinking it's a transformer. It has a fair amount of weight to it. I'd say 5-6 ounces at least. Anyway, I'll go to Grainger on Monday and get this particular part. Also worth noting... the green T-stat wire that is on this transformer or what ever it is, had electric tape for the last 3 inches leading up to the contact. When I replace this part, I'm going to take off that electric tape to see why it's there.

Sounds like you may have a couple of control problems... maybe a fan switch going bad or even a limit switch that is opening in the heat of the attic. Shouldn't happen, but some of these problems are so intermittent that troubleshooting can be a real problem. Unfortunately the best way to locate the problem is when it fail... in the midst of a sweltering attic. If you leave the fan switch in "on" will the fan run constantly or will it still cycle off?

A capicitor for blower shouldn`t cost $5,, is worth trying,, I get them for less than $2,, just make sure you kill the power and ground out the terminals before handleing,

a capicitor for blower shouldn`t cost $5,,,, is worth trying,,,I get them for less than $2,,,,just make sure you kill the power and ground out the terminals befor handleing,,
Wow! Where do you get motor start/run capacitors this cheap? I may have a new favorite store!

Wow! Where do you get motor start/run capacitors this cheap? I may have a new favorite store!


Buy them by the dozen,, Johnstone Supply

Sounds like you may have a couple of control problems....maybe a fan switch going bad or even a limit switch that is opening in the heat of the attic. Shouldn't happen, but some of these problems are so intermittent that troubleshooting can be a real problem. Unfortunately the best way to locate the problem is when it fail.....in the midst of a sweltering attic. If you leave the fan switch in "on" will the fan run constantly or will it still cycle off?

Misso - Yes, if I push the fan mode, not auto, the fan/air handler comes on and stays on as long as I do it in the morning.. 7:00 AM or so before the attic heats up. If I wait until 10:00 AM or so, the air handler won't come on. If I leave it in auto and push the cool button, the outside compressor goes on but the air handler in the attic does not. Interestingly, once it's on, it will run for days cycling on and off after reaching the set tempature even with the heat of the attic. The key is turning it on before it's too hot in the attic. I was at several HVAC places today, and most couldn't get this transformer part and some couldn't sell to me because I wasn't a contractor. However several said that either the transformer works or it doesn't. So I guess I can rule out the transformer. This York central air cond is cool only. We have baseboard heat. I'm wondering if the compressor outside has any say on if the air handler comes on or not. That is in an area that get's little sun first thing in the morning but then gets blasted by the sun until 12:00 or so. Well maybe some connections of this transformer were loose and when I put it back in everything will work.

a capicitor for blower shouldn`t cost $5,,,, is worth trying,,,I get them for less than $2,,,,just make sure you kill the power and ground out the terminals befor handleing,,

WM - I replaced the capacitor but no dice.

Wow! Where do you get motor start/run capacitors this cheap? I may have a new favorite store!

Wally - I paid $4.60 for the capacitor at Grainger. Fortunatly they had my company as a customer otherwise they wouldn't have been able to sell to me. They're only business to business.

Wow! Where do you get motor start/run capacitors this cheap? I may have a new favorite store!

Wally - Does the outside compressor have any say as to if the air handler in the attic turns on? i.e. any controls in the outside unit that might be bad causing this problem in the air handler?

Well in case you want to purchase parts yourself, there are PLENTY of supply houses that sell online to consumers. HVAC Parts Outlet (http://www.hvacpartsoutlet.com) is one of them. Can you give the MFG info on the unit itself? I'd like to see a schematic. But I still think it's a matter of replacing parts until you fix the problem, unless you can troubleshoot it while it's failed.
Good luck!

Wally - Does the outside compressor have any say as to if the air handler in the attic turns on? i.e. any controls in the outside unit that might be bad causing this problem in the air handler?
I'm not 100% positive, but I think that all the control is done in the thermostat itself. It commands the compressor to turn on, as well as the blower.

Wh

Wally - I paid $4.60 for the capacitor at Grainger. Fortunatly they had my company as a customer otherwise they wouldn't have been able to sell to me. They're only business to business.
Yeah, I bought my capacitors at Grainger too, but they were about $12. They were dual units, one for the compressor and one for the fan in a conventional HVAC system. To tell you the truth, I was happy to pay that. I can buy a lot of those for the price of a service call!

Good luck up there,
WallyH

Yeah, I bought my capacitors at Grainger too, but they were about $12. They were dual units, one for the compressor and one for the fan in a conventional HVAC system. To tell you the truth, I was happy to pay that. I can buy a lot of those for the price of a service call!

Good luck up there,
WallyH

I believe I got a corporate discount due to my employer being in their data base.

Well in case you want to purchase parts yourself, there are PLENTY of supply houses that sell online to consumers. HVAC Parts Outlet (http://www.hvacpartsoutlet.com) is one of them. Can you give the MFG info on the unit itself? I'd like to see a schematic. But I still think it's a matter of replacing parts until you fix the problem, unless you can troubleshoot it while it's failed.
Good luck!

I will. I'll be back up there Friday... loosing a few pounds in the blistering heat of the attic, to put the old transformer back in. I noticed on the air handler that there was a sticker with information on it. I'll right it down and let you know. I know that it's a York around 9 years old but I'll get more detailed info.

Sounds like you may have a couple of control problems....maybe a fan switch going bad or even a limit switch that is opening in the heat of the attic. Shouldn't happen, but some of these problems are so intermittent that troubleshooting can be a real problem. Unfortunately the best way to locate the problem is when it fail.....in the midst of a sweltering attic. If you leave the fan switch in "on" will the fan run constantly or will it still cycle off?

Misso - the fan switch... is that literally a on-off switch? Up at the blower, the main power goes to a light switch... it looks like a regular 2-pole type on-off light switch. From there it goes to the transformer. Is it possible that this switch would be affected by the heat of the attic?

Misso - the fan switch... is that literally a on-off switch? Up at the blower, the main power goes to a light switch... it looks like a regular 2-pole type on-off light switch. From there it goes to the transformer. Is it possible that this switch would be affected by the heat of the attic?
I'll jump in here...
My guess is that this switch is just for safety. You can kill power to the blower so it would be safe to stick your hands in there. I would seriously doubt this would contribute to the problem, but while you're replacing things it would be a cheap experiment. Just kill power at the breaker beforehand!

WallyH

NO. The fan switch on the thermostat is just a control. There will be a contactor of some sort that the fan switch controls in the air handler. On my heat pump, for example the fan would continue to run after the air conditioner was satisfied. It turned out to be a fan switch (relay) which was sticking. After replacing it the switch worked normally. And some furnaces have a fan control which sensed heat rise after a burner fires up and starts the fan and allows it to run after the furnace flame kicks off to circulate and to cool the heat exchanger.

NO. The fan switch on the thermostat is just a control. There will be a contactor of some sort that the fan switch controls in the air handler. On my heat pump, for example the fan would continue to run after the air conditioner was satisfied. It turned out to be a fan switch (relay) which was sticking. After replacing it the switch worked normally. And some furnaces have a fan control which sensed heat rise after a burner fires up and starts the fan and allows it to run after the furnace flame kicks off to circulate and to cool the heat exchanger.

Misso - The Air Handler is a York Model # N4AHD14A06A Serial # EDFS098644 - unit supply 208/230 volts 60 hz. Again, it's cool only. We have baseboard heat. I'd say that it's 10 years old or so. We've been in this house 8 years. The former owner had this installed a few years prior to us buying this house. There's also a number up on the right side of the tag LR49182C. So right now, 8:30 AM, I've put the fan on, and it's running fine because the attic isn't hot at this time. After it gets a little hotter today, I'll click on the cool and the central air will work fine even though the attic will be sweltering. If I turn it off mid day and then try to turn it back on... no dice, the air handler won't come on but the outside compressor will run?? Question... a transformer either works or it doesn't? Ther's no it works sometimes and sometimes not... yes? This is what one of the supply house workers told me. He didn't think it was the transformer because it works in the morning.

I'll jump in here...
My guess is that this switch is just for safety. You can kill power to the blower so it would be safe to stick your hands in there. I would seriously doubt this would contribute to the problem, but while you're replacing things it would be a cheap experiment. Just kill power at the breaker beforehand!

WallyH

So... strange but true. I turned the fan to "on" Saturday morning just to make sure the air handler would go on. I didn't set the control to "cool" until around 11:30. It's been running like that with no problem since Saturday morning and still Monday evening. The outside compressor cycles on and off when it hits the set temperature but the air handler stays on obviously because I have it set to on instead of auto. However, if I turn the air off this evening and try to turn it back on tomorrow afternoon when the attic is hot... butkus! No air handler.

I can't find any schematics for your air handler. But maybe you can answer this... when you open up the service panel of the unit, is there a circuit board which the thermostat wiring connects to, or are there various components the stat wiring is directed to? Does the switch on the thermostat ALWAYS turn on the fan when placed in the on position? Does the fan start immediately when in the auto position and the thermostat calls for cool? If the fan relay is good, perhaps... and it's a strong perhaps that you have a voltage problem... any chance you can check the voltage at the fan relay, and at the thermostat?

I can't find any schematics for your air handler. But maybe you can answer this.....when you open up the service panel of the unit, is there a circuit board which the thermostat wiring connects to, or are there various components the stat wiring is directed to? Does the switch on the thermostat ALWAYS turn on the fan when placed in the on position? Does the fan start immediately when in the auto position and the thermostat calls for cool? If the fan relay is good, perhaps...and it's a strong perhaps that you have a voltage problem....any chance you can check the voltage at the fan relay, and at the thermostat?

Main power goes to a regular on off switch. Then white & black go to the transformer. Also at the bottom of this on-off switch is a small circular type thing with two connectors on it. I think it might be a limit switch type thing? The T-Stat wires, green & red connect to the transformer (yellow isn't connected and electric taped with a loop at the end, so as not to expose the end of the wire... cool only) Then from the transformer, there are 2 wires that connect to a smaller circuit board that has a little black box on it. I was going to replace this transformer but apparently it's a special part that I would have to get from York directly. I've been told however that either the transformer works or it doesn't. There's no in between. Do you agree with that?

The fan will start immediately in either "on" or "auto" when cool is pushed... if the attic isn't to hot. Once the attic reaches a certain temperature, the fan doesn't go on. No sound or anything, just no fan. For instance... on Saturday, I turned the fan to "on" early in the morning because we were having a party and I wanted to make sure that we had the central air working. I didn't set the t-stat to cool however. The fan came right on with no problem. I left it on then around 1:00 with the attic already sweltering, I clicked on the cool. The outside compressor came on and because the blower was already going, magic we had central air. I let it run like this until this morning when the humidity and heat finally cleared out. The compressor cycled on & off all week but the only difference was I left the blower to "on"??

Main power goes to a regular on off switch. Then white & black go to the transformer. Also at the bottom of this on-off switch is a small circular type thing with two connectors on it. I think it might be a limit switch type thing?? The T-Stat wires, green & red connect to the transformer (yellow isn't connected and electric taped with a loop at the end, so as not to expose the end of the wire...cool only) Then from the transformer, there are 2 wires that connect to a smaller circuit board that has a little black box on it. I was going to replace this transformer but apparently its a special part that I would have to get from York directly. I've been told however that either the transformer works or it doesn't. There's no in between. Do you agree with that?
Can we get a photo of that round thingy? (and the circuit board, if you're taking pics anyway).
I agree that it would be unlikely that a transformer would have a temperature sensitivity, so I'd put that on the back burner for now. I'd concentrate on any electronic items that are subject to the attic heat.

We won't let this stump us!
WallyH

Can we get a photo of that round thingy? (and the circuit board, if you're taking pics anyway).
I agree that it would be unlikely that a transformer would have a temperature sensitivity, so I'd put that on the back burner for now. I'd concentrate on any electronic items that are subject to the attic heat.

We won't let this stump us!
WallyH

Absolutely... I'll go up there this weekend and get the pics!

I suspect that the "little black box" is probably a fan relay, unless you have one mounted somewhere else in the unit. And I suspect that if the board has the fan relay on it, you probably will need to replace the board.

Pictures will help and any numbers available on any parts would help as well.

Wally - Here's the pic of the board with the potential relay on it.

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Absolutely... I'll go up there this weekend and get the pics!

The pic is posted.

I suspect that the "little black box" is probably a fan relay, unless you have one mounted somewhere else in the unit. And I suspect that if the board has the fan relay on it, you probably will need to replace the board.

Pictures will help and any numbers available on any parts would help as well.

The pic is posted.

The pic is posted.
Sorry for the delayed reply... I just got back from vacation (7/16-7/22).
That does look like a relay, and I could believe that a component like that would be more susceptible to heat than the other resistors, capacitors, etc. Unfortunately, you can't be certain without swapping it out--which probably requires a whole new (unreturnable) circuit board.

Earlier you mentioned a round thing. Did you happen to get a photo of that too? I'm guessing that is some type of thermal switch/fuse, and might be suspect.

I sure hope it isn't as hot where you are as it is where I was!
WallyH

Sorry for the delayed reply...I just got back from vacation (7/16-7/22).
That does look like a relay, and I could believe that a component like that would be more susceptible to heat than the other resistors, capacitors, etc. Unfortunately, you can't be certain without swapping it out--which probably requires a whole new (unreturnable) circuit board.

Earlier you mentioned a round thing. Did you happen to get a photo of that too? I'm guessing that is some type of thermal switch/fuse, and might be suspect.

I sure hope it isn't as hot where you are as it is where I was!
WallyH

Hi Wally - I hoped you enjoyed your vacation. Yes, it was pretty darn hot up there. Crud, I can't believe I forgot to take a pic of the thermal switch thing. I forget where I saw it, but it looked allot like a limit switch... I think. I'll get up there again this weekend and get a pic of it. By the way, the air has been on for a week straight now without any problems. As I had mentioned, I have to keep the fan in the "on" position however instead of auto.

Hi Wally - I hoped you enjoyed your vacation. Yes, it was pretty darn hot up there. Crud, I can't belive I forgot to take a pic of the thermal switch thing. I forget where I saw it, but it looked allot like a limit switch...I think. I'll get up there again this weekend and get a pic of it. By the way, the air has been on for a week straight now without any problems. As I had mentioned, I have to keep the fan in the "on" position however instead of auto.

Hi Wally - You still here?

TIS PROBLEM WAS 8 MONTHS AGO,, surely it has been fixed by now

Hi Wally - You still here?
I am still monitoring this problem... and hope you have indeed found the problem. This has been quite a mystery, and I'd like to know the resolution for my own information.

WallyH

What you can do is when the fan kills out. Turn the power of and feel the back of the motor. If the motor is to hot to touch then you need a new motor, if it is relatively cool. The odds are it is the fan relay on your circuit board.

Did you ever get this fixed??

Did you ever get this fixed?????

No, not fixed. I'm going to attach a pic of a switch that is on the air handler that has a black circular resistor type thing that has two wires on it. Maybe someone can tell me what that is. Last year, we lived with the fact that we had to turn the air on in the morning before it got hot in the attic. I'd like to fix it this year however. Stayed tuned while I try to remember how to attach a picture here.

What you can do is when the fan kills out. Turn the power of and feel the back of the motor. if the motor is to hot to touch then you need a new motor, if it is relatively cool. The odds are it is the fan relay on your circuit board.

Here in lies the problem. Once the airhandler is on, it will run until I turn it off. Just as long as it goes on before the sun starts to heat up the attic. Last summer I was able to turn on "fan only" around 6:30AM. Then when I got home from work, I clicked on the air portion and everything is cool. At one point, it ran for almost a week straight because of a heat spell. If I tried to turn it on when I got home from work however, no dice, the outside condenser comes on, but not the air handler.

no, not fixed. I'm going to attach a pic of a switch that is on the air handler that has a black circular resistor type thing that has two wires on it. Maybe someone can tell me what that is. Last year, we lived with the fact that we had to turn the air on in the morning before it got hot in the attic. I'd like to fix it this year however. Stayed tuned while i try to remember how to attach a picture here.

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This is an on/off switch located in the attic on the outside of the air handler. One shot is the bottom of the switch and one is inside the switch. Unlike regular light switches, this has that black circular thing with the 2 light blue connectors on it.

Have you ever felt the fat motor to see if it was extreamly hot? Soory I am new to this question but would love to help. And that pic you just put up looks like some sort of limit

Sounds to me like the cooling fan relay is going, or has gone bad.

sounds to me like the cooling fan relay is going, or has gone bad.

But why would the cooling fan relay work when the temperature in the attic is cooler. Is this fan relay heat sensitive? It seems that once the blower is going, it keeps going.

If it's too hot in the attic, and I flip on the air, the outside condenser comes on, but the air handler doesn't. I replaced the capacitor on the blower already and that wasn't it. I've been told that relays either work or they don't. Are limit switches heat sensitive?

As I said, if I turn on the central air in the morning before I go to work... before the sun heats up the attic, the air handler & outside condenser will run fine for days. For instance, if I turn on the central air now and turn it cool enough so that it comes on, I'll have no problems because there isn't any heat in the attic yet.

I am still monitoring this problem...and hope you have indeed found the problem. This has been quite a mystery, and I'd like to know the resolution for my own information.

WallyH

Wally, I posted the picsfof that switch and the limit type device under it. Could the heat affect this? It almost would make sense. If power doesn't flow through this switch, obviously no power to the blower.

The limit switch should have no purpose during the cooling cycle.

Also I am a Factory York dealer so if you airhandler is york let me see what I can come up with.

I Should be back on this afternoon and let you know what I found.

Ok so far the control board you have there is acctually called a electric heat control. So there may be something on it locking you out. Your t-stat wires do not connect to this control do they? Also I would like to know where the two wires coming out of that little black switch conect to.

Ok so far the control board you have there is acctually called a electric heat control. So there may be something on it locking you out. your t-stat wires do not connect to this control do they? Also i would like to know where the two wires comming out of that little black switch conect to.

Josh - Yes it's a York around 10-11 years old. I don't think the t-stat wires are in or attached to this switch but I'll have to go up and check as I haven't been up there since last August. I'm attaching a pic of all 3 components on the outside of the air handler. I tried to get the circuit board from some of the local vendors but nobody seemed to have it and most wouldn't deal with me because I'm not a plumber. I did replace the capacitor as that was the most obvious culprit but that wasn't it. The silver square piece hanging down is the face plate of the on/off switch.

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also i am a Factory York dealer so if you airhandler is york let me see what i can come up with.
Josh is going to be a MUCH better resource than I will be. I am simply a very handy (retired engineer) homeowner. I defer to an expert. :o

Josh is going to be a MUCH better resource than I will be. I am simply a very handy (retired engineer) homeowner. I defer to an expert. :o

Thanks Wally... I appreciate your help.

You say all these controls in the pic are outside of the unit? I am trying to find out just what exactly that little black switch is so far no luck. But still looking

These intermitant problems are always the toughest to figure out.

you say all these controls in the pic are outside of the unit? i am tring to find out just what exactly that little black switch is so far no luck. but still looking

Yes. I say outside, but I had to take off the cover on the right side of the air handler. This revealed the components you see in the picture. As far as I can tell, this light switch looking switch has to be there so a tech can shut the power off before servicing the unit? My thoughts are to bypass this switch. Tie the power directly to the unit so this switch isn't in the picture. Of course, I won't know if this is successful until the temperature in the attic get's hotter.

Would the outside condenser have anything to do with this? A few years back, a capacitor went in this unit. The air handler continued to operate but blew warm air because the outside unit wasn't operational. It was rather obvious that the capacitor was shot because it looked liked a M-80 went off in it. I replaced that and all was OK.

Nothing on the out door unit would cause your airhandler to shut off. The light switch you speak of should be just a on and of switch. So you do not get shocked will working on the unit. So I do not think the light switch is the problem. You have 2 relays 1 built into the transformer, and a fan really that is the black one built onto the circuit board. When you say to get it to run and cool your house all day do you mean by turning the ac on early and turning it way down to like 65 or so? Or do you mean you turn the fan switch from auto to the on position? I know you attic is probably not hot enough right now for anything to happen. But when it does warm up. Try just turning the fan to the on position and leaving the t-stat set at normal 72 or where ever you keep it. If it stays cool and works like that then it is a 90% chance the problem is in the transformer really.

Nothing on the out door unit would cause your airhandler to shut off. the light switch you speek of should be just a on and of switch. so you do not get shocked will working on the unit. so i do not think the light switch is the problem. you have 2 relays 1 built into the transformer, and a fan realy that is the black one built onto the circuit board. When you say to get it to run and cool your house all day do you mean by turning the ac on early and turning it way down to like 65 or so? or do you mean you turn the fan switch from auto to the on position? I know you attic is probally not hot enough right now for anything to happen. but when it does warm up. try just turning the fan to the on position and leaving the t-stat set at normal 72 or where ever you keep it. If it stays cool and works like that then it is a 90% chance the problem is in the transformer realy.

The t-stat is digital. Honeywell (I replaced that too by the way). On the left side of the display is Auto & On... 2 selections. On the right, heat & cool. We have baseboard heat, so the heat selection obviously doesn't get used.

We use to set the air to auto, cool and set the temp to 70 in the morning when the attic was cool. That worked for several years. Last year however, what would happen is the temp would reach the 70 and the air would turn off. Once the temp went above the est point the outside unit would come on, but not the air handler. This created a fairly decent flood into the insulation and stained the ceiling above where the air handler is. So then what I did was turn the control to "on" but not set it to "cool". The air handler would come on but not the outside unit. I would do this around 6:30 AM. When my wife got home from work at 4:00 PM the air handler would still be running but the house would be up above 80 because the t-stat was not set to cool. She would then go t-stat and set the control to cool but leave the left side at "on" not "auto". Upon doing so, the outside unit would come on and proceed to cool the house.

As I had mentioned, during a heat wave last year, we left it in the above configuration for at least a week straight. Because the unit was set to "on" and not "auto" it wouldn't shut off if it hit the selected temp. If for some reason it shut off, and I tried to turn it back on, the outside unit would come on, but no air handler until the attic cooled.

So what ever the problem is with the air handler, it's heat related.

By the way, I've had the pro's out twice to look at it and both concluded there's nothing wrong and I must be nuts, because there's no thermistor's or any thing like that in the air handler that would not work intermittlently due to heat.

Last year I took that transformer to several HVAC places but they either didn't have it, or wouldn't sell it to me because I'm not a licensed plumber.

One of the guys at a HVAC joint said that it couldn't be the transformer because they either work, or they don't. Heat wouldn't have any effect on it. I told him a beg to differ and basically he told me I'm a stupid home owner that shouldn't be in their store.

A regular transformer does either work or it doesn't, but you have a trransformer/relay combo. Well as I was saying if it runs fine on the fan on setting, with the cool on. But not the auto setting with the cool on. Then the relay at the transormer is getting hot and not kicking in. What happens is when there is a call for heat the t-stat will send power to your outdoor unit. Thus the outdoor unit comes on. But the t-state does not send power to the blower. That is why the really kicks in to tell the fan to come on. When you have turned it to the on position you have bypased that really and it works good. So from what I am thinking. The stupid home owner as you said had it figured out last year and the people at the heating company are really the stupid ones. What state are you located?

I think Josh is leading you in the right direction. Nothing I can add here. Good luck and please let us know what he final outcome is.

If you are deadset on doing this yourself, it may be a matter of replacing parts until problem is fixed. I hate to do it that way, but sometimes you just have to do it. I would start with Joshes advice(replace trans, relay). Its your best bet at this point.

A regular transformer does either work or it doesn't, but you have a trransformer/relay combo. well as i was saying if it runs fine on the fan on setting, with the cool on. but not the auto setting with the cool on. then the relay at the transormer is getting hot and not kicking in. What happens is when there is a call for heat the t-stat will send power to your outdoor unit. thus the outdoor unit comes on. But the t-state does not send power to the blower. that is why the realy kicks in to tell the fan to come on. when you have turned it to the on position you have bypased that realy and it works good. So from what i am thinking. The stupid home owner as you said had it figured out last year and the people at the heating company are really the stupid ones. what state are you located?

I'm in South Windsor, CT. 10 minutes norteast of Hartford. Any suggestions as to where I might get my hands on this transformer/relay combo?

Sorry I have been super busy and have not been on that much. I will get you the exact part number you should need. Then just look up at york .com and find the closest york dealer near you they should have it or be able to get it with in a day.

OK I finally got some info for you. The original circuit control for that airhandler was called electronic heat control board. Sense you do not have heat in your unit it was replace by what is called a blower delay timer. When you turn you fan to the on position. That elimanates your blower timer. So I would defentally say it is the little circuit board that is causing your problems. The part number for this is S1-02425800700. If you look up york.com or source1.com they can give you the closest york dealer. Also just so you don't get screwed around I would charge $37.56 for this board plus tax. So prices may be a little higher in your area but I would not pay mre the $50 for it. If you have any other questions feel free to ask I should be on later. Or email me direct at [email protected] Have a good day Josh

ok i finally got some info for ya. the original circuit control for that airhandler was called electronic heat control board. Sence you do not have heat in your unit it was replace by what is called a blower delay timer. When you turn you fan to the on position. that elimanates your blower timer. so i would defentally say it is the little circuit board that is causing your problems. the part number for this is S1-02425800700. If you look up york.com or source1.com they can give you the closest york dealer. aslo just so you don't get screwed around i would charge $37.56 for this board plus tax. So prices may be a little higher in your area but i would not pay mre the $50 for it. If you have any other questions feel free to ask i should be on later. or email me direct at [email protected] Have a good day Josh

Josh - You da man! I'll be up in the attic this weekend to get that bad boy out. As soon as the attic heats up, we'll get our answer. I'll keep you posted on my quest for the board. Thanks

Cool, keep me posted. Hope it works for you!!

Any luck retreving that fan timer board?

I've called 2 HVAC places that were listed in source1parts, but neither have gotten back to me. I left messages with their answering services. I'm not holding my breath that thye'll get back to me. I didn't see where I could order the part on that source1parts.com or york.com. There's a place in Hartford, I forget the name, but I should have luck there. It's like a Gray Bar kind of place. I should have time to stop by tomorrow. As it turns out, the company I work for, Ricoh Americas Corporation has an account with them. Otherwise they wouldn't have sold me a capacitor last summer. I'll give them a try.

Josh - Using the part number you gave me, I found the relay at Grainger. Or I should say that they are ordering it from York for me. I should have it in a week 1/2. I'll keep you posted after install to see if does the trick.

Josh - I put the part in this weekend. It was kind of hot up in the attic, but not hot enough for the official test. The good news is everything came on after installing the part. Now I just have to wait for the attic to heat up to see if the blower is going to come on.

I'll keep you posted

Great, lets keep our fingers crossed

Ta da da da ta da!! Josh you are the man. The 2 year odyssey has been solved.

The temperature today was 91, so obviously the attic was steaming. I turned the central air control to cool, and presto magic, outside condenser with air handler on together the way it's suppose to work.

Just a re-cap... if the attic temperature was above 80 or so, the outside condenser would come on but not the air handler. Obviously that defeats the purpose of central air.

Josh figured out from just a few posts that my problem was the fan relay switch (I might have the technical name incorrect) Josh not only identified the problem, but gave me the part number as well.

Thank you Josh! Let me know if you want me to rate your answer or something. I've seen that below certain peoples names.

91 that's getting hot, glad it is working. You can rate at the bottom of the post if you like. If you don't mind me asking how much did you end up getting the control for?

I'll let you know exactly, but with shipping it was about $47 or so, maybe a little less. I'll get my statement and let you know.

That's not bad at all, I think I said like $35 plus shipping

Right on. I got it from Grainger. As it turns out the company I work for , Ricoh Americas Corporation has an account with them. Otherwise, I would have been SOL because I'm not a licensed HVAC... etc.

Well sounds like you lucked out then. Now you can injoy some nice cool air this summer. If you ever have any other problems look me up. Have a great weekend!!

Cased closed!! What a great site. If I didn't stumble upon thi site, I would have paid several more HVAC companies to tell me that my problem doesn't exist.

Thanks to all that participated, with special thanks to Josh.

I actually wish that I wasn't in sales, and was a plumer, electrcian or HAVC person. I like doing that stuff myself and take satisfaction in fixing it myself.

Bill Stanley

Consider yourself one now. Job well done!!

Having the same problem

I have an old York air exchanger located in the attic of our small ranch. I came home to find the exchanger circuit breaker tripped. When I turned it on, I could hear a low humming sound, but when I turned the blower on manually, I did her a "click" but the blower didn't run. The outside condenser will run, but no blower.

I took the side panel off the echanger to see if the fan was frozen. It is not. Otherwise, I could see nothing out of the ordinary, but then, I don't know what I am looking for. Thanks for any help.

Wally