[bstanley]

[attach]Attachment 18411[/attach]

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.

[Joshdta]

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

[Joshdta]

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

[bstanley]

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.

[bstanley]

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.

[Joshdta]

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

[Joshdta]

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

[Joshdta]

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

[Joshdta]

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.

[bstanley]

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.

[WallyHelps]

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

[bstanley]

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.

[Joshdta]

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

[Joshdta]

These intermitant problems are always the toughest to figure out.

[bstanley]

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.

[Joshdta]

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.

[bstanley]

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.

[Joshdta]

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?

[mygirlsdad77]

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.

[bstanley]

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?