Ask Me Help Desk - Heat Pump will not shut off

Heat Pump will not shut off

I have a Bryant heat pump that was used very little over the winter. When I went to turn on the air conditioning a few days ago, the outdoor unit would not come on, but the indoor fan and thermostat appeared to be working fine.

I checked the contactor and it was not pulling in, when I pushed it in, the unit kicked on, but would not shut off when I turned it off at the thermostat. I had to cut the power to turn it off as to not damage the compressor.

I replaced the contactor with an identical contactor from the Bryant dealer. It was definitely bad. When I turned the power back on to the outdoor unit, it would not shut off, even when the contactor is not pulled in and the thermostat is off. I had to cut the power again.

I am 100% sure that I replced the wires correctly on the new contactor. What is the next logical thing to check?

Thanks,

Scott:confused:

What continues to run? The compressor and the fan or both? If only the fan, it could be the defrost relay. Just ran into this problem recently.You are sure it's wired correctly? Just verifing

Quote:

Originally Posted by esquire1

What continues to run? The compressor and the fan or both? If only the fan, it could be the defrost relay. Just ran into this problem recently.You are sure it's wired correctly? Just verifing

Thanks for the response.

It is the outdoor compressor and the outdoor fan that continue to run even when the thermostat is not on. I cannot turn off the outdoor unit off unless I trip the breaker. The outside contactor is not pulled in while it is running.

I can turn the inside fan off by turning off the thermostat, but the outside unit continues to run. If I turn the breaker back on outside, the outdoor unit will still start up immediately even when the thermostat is off and the contactor is out. Very strange!

I wired the new contactor the same way the old one was wired. I moved the wires one at a time to be safe. I even snapped a picture before I switched it. This unit was operational last year, and nothing else has changed.

Scott

You are sure that the compressor is also running? You hear it run? You put your hand on it and it's hot and you feel it running? Not trying to be rude but just trying to help you get it going.

Quote:

Originally Posted by esquire1

You are sure that the compressor is also running? You hear it run? You put your hand on it and it's hot and you feel it running? Not trying to be rude but just trying to help you get it going.

I will double check when I get home tonight. It sounded like it was running. I will have to pull back the cover on it when I get home in a few hours and see if I feel it running and it is warm.

I do know that more than just the fan was running. I assumed that the other louder noise coming from the unit was the compressor. It sounded like it did when it worked last year and I listened to the neighbors unit and it sounded the same.

Thanks,

Scott

When you have the cover off, also look at the wiring coming from the compressor and fan and double check them. Be sure they are connected to contactor opposite end as the 220 volts coming from the disconnect. In other words. You will have 220 volts at the bottom of the contactor and 0 volts at other end with contacts open. When 24 volts pull the contactor in, 220 volts at both ends. It is this end where power should be delivered to compressor and fan. I hope I have not confused you now.

Not confused at all. I have the fan and the compressor cables plugged into the opposite end of the source as they were. Here are some pictures (with old contactor). I have it hooked up exactly the same as the new one though.

http://www.shoemaker.us/temp/panel1.jpg
http://www.shoemaker.us/temp/panel.jpg

I will retrace all of these cables to see if I can figure how this fits together. When I get home. I will check the voltage at the top with the contacts open.

Thanks,

Scott

That is a single pole contactor, so you will have 120 volts at the top all of the time, the contactor only breaks one leg. Take a picture of the schematic and post it if you can.

Quote:

Originally Posted by hvacservicetech_07

Take a picture of the schematic and post it if you can.

Yes, it is a single pole contactor. Here is the schematic picture.

http://www.shoemaker.us/temp/schematic.jpg

Also, I have again verified that the compressor and fan are both running with the thermostat off and the contactor open.

Thanks again for the help!

Scott

You may have a bad crank case heater on the compressor. Undo the wires that go to it.the two black wires that go to the bottom of the compressor.One goes to L1 and the other to 21 on the contactor. If the compressor heater goes bad it can keep 240 volts on the 21 and 22 side of the contactor. It turns into a jumper wire from L1 to 22 and makes the unit run all the time.

Quote:

Originally Posted by T-Top

If the compressor heater goes bad it can keep 240 volts on the 21 and 22 side of the contactor. It turns into a jumper wire from L1 to 21 and makes the unit run all the time.

From looking at the diagram, this makes sense. Interesting. I will go out and try it when it is daylight. If this is the problem, what is the approximate cost of replacement, and is it easy to change out?

After I unplug the heater, and if the unit is off when I turn on the breaker (as it should be with the T-stat off and the contactor open), should I try to kick it on at the T-stat to see if the contactor pulls in and it turns on?

Thanks a lot!

Scott

You got it right my man. But remember this is a test(trial and error). Yes you can get a wrap around compressor heater from any hvac supplier and wire it back in the same way. Good luck.

Did you by chance test any voltages yet?

The voltage at 21 and 22 has to be 240 volts or it would not be running. The question is why is it with out the contactor closed.

I see your point, but aren't crankcase heaters usually wired to L1 and L2, otherwise, what would be the point? It almost sounds like the contactor is shorted, Ive looked at the pictures, everything looks right...

Ok, I'm looking at the contactor right now, there is nothing on L1 and L2 besides line voltage, so there doesn't seem to be any way for a crankcase heater to be feeding voltage through, in my opinion the only way it's getting power is a shorted contactor, how else could it be getting 240 volts at 21 and 22?

If the crankcase heater was on L1 and L2 they would be on all the time no need to be heating and adding extra amps after the compressor is running.

T-Top, am I looking at this wrong though? Do you see anything else on L1 or L2? I must be over looking something, unless the contactor is really pulling in...

Keep looking check out the wire schematic he sent.

Any time I add an after market CCH ,I always install it on L1 and L2 exspecially if it's just air conditioning running all winter, otherwise you'd have a compressor trying to start with cold oil?

I see how it's wired on the schematic, but I don't see anything on the line side of the contactor besides the line voltage, that's what has me confused.

I hate to say it but your wrong the crank case heater is hot when the contactor is open not calling for heat or cooling keeping the oil warm in the compressor but when the contactor closes the heater drops out.

Quote:

Originally Posted by T-Top

I hate to say it but your wrong the crank case heater is hot when the contactor is open not calling for heat or cooling keeping the oil warm in the compressor but when the contactor closes the heater drops out.

I found this at the following link. You are correct T.

Compressor Crankcase Heater

"Some manufacturers of AC equipment install crankcase heaters either in the compressor or mount them externally around the base of the compressor. The (2) wires of the heater is wired directly to the 230 Volt input side of the contactor from the main power supply, and is always supplying 230 volts of power to the heater. "

I am going to go out and look at it now. I will let you know what I find out.

Thanks again!

Shoe

What you guys are discusing is over my head. All that I know is that last summer my heat pump turned on by itself (in the heat mode) while the thermostat was in the off position. The only way I could turn it off was by tripping the breaker. I replaced the 10 year old Honeywell programmable thermostat, and solved the problem.

Ok, I went outside and looked at the unit. I do not think that this unit has a crankcase heater unless I am missing something. I am assuming that if there were, that it would be plugged into the bottom of the contactor. There are no cables there. There was a thermal cover on the compressor which I removed.

After I turned on the breaker and the unit kicked on, I checked the voltage coming in and it read 240 (11 and 23). I also checked the voltage across 21 and 23, and it read 120.

Thanks for the suggestion Dr D.

I unplugged the wiring that leads inside the house (disabling the thermostat), and the thing still kicked on when I turned on the circuit breaker. Ugh!! This is weird...

I put some additional pictures up online of the contactor

http://www.shoemaker.us/temp/contactor.jpg

And the inside components
http://www.shoemaker.us/temp/inside1.jpg
http://www.shoemaker.us/temp/inside2.jpg
http://www.shoemaker.us/temp/inside3.jpg

Scott

I also disconnected the wires from my old TS. That did not shut off the HP. It was only after I hooked up the new TS that it shut down. Why, I don't know.

In the pic you sent of the contactor it looks like it is in the closed position. Do you have 24 volts on the low voltage side of contactor?(check yellow and black wires on sides of contactor)

Quote:

Originally Posted by T-Top

In the pic you sent of the contactor it looks like it is in the closed position. Do you have 24 volts on the low voltage side of contactor?(check yellow and black wires on sides of contactor)

Yes, in the picture, it does look closed. I also thought that it looked that way when I posted it. I can assure you that it is open, though. It is brand new and springs back when I manually push it in with the breaker off. There is no contact between the metal contact points until I push it in.

I checked the voltage between the yellow and brown wires (on the sides), and it was not 24V. It was negligible.

Thanks for the help.

Scott

Looks like you have a refrigerant leak by all the oil in the bottom of the condensing unit. Unless it is just old wet leaves. It also looks like oil residue on the copper line in the picture. Interesting.

There is no crankcase heater. I agree, it looks oil to me as well.

If you only have 120 volts at the top of the contactor when it's open, that is OK, it's a single pole contactor so it only breaks one leg. Something is strange here. Pull the small wire off the right side of the contactor, then power it up, does it come on?

No oil, just wet leaves.

I pulled the yellow wire off on the right side, and it still came on.

Ok, disconnect and tape off the two wires on the top of the contactor that are behind the screws, power it up, does it run?

Something is back feeding somewhere.

Quote:

Originally Posted by hvacservicetech_07

Ok, disconnect and tape off the two wires on the top of the contactor that are behind the screws, power it up, does it run?

No, it does not run, but you can hear a hum.

Also, there might be a little oil on the bottom in the leaves. I cleaned out the leaves and some of them were pretty dark. My fingers were a little greasy as well.

You may have a small leak, but that won't keep it running, try switching both yellow and black wires on the top of the contactor, and let me know what that does, I'm trying to pinpoint what exactly is back feeding.

Quote:

Originally Posted by hvacservicetech_07

You may have a small leak, but that won't keep it running, try switching both yellow and black wires on the top of the contactor, and let me know what that does, I'm trying to pinpoint what exactly is back feeding.

OK, Fan started, but compressor only hummed, probably because it was bypassing the capacitor.

In one of your pics it looks like the condenser fan wire is not on the defrost relay. I see the power in but not the black wire for the fan motor. Give us a pic of the top side of the run capacitor so we can see the wires. It is a back feed problem and a easy fix but just hard to do from the PC. Don't give up your close.

Quote:

Originally Posted by T-Top

Give us a pic of the top side of the run capacitor so we can see the wires. It is a back feed problem and a easy fix but just hard to do from the PC. Dont give up your close.

Here is the pic.

http://www.shoemaker.us/temp/cap.jpg

Thanks again. This is very strange...

Shoe