Trouble with Goodman Heat Pump contactor


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Old 12-18-22, 08:28 PM
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Trouble with Goodman Heat Pump contactor

I was having trouble with my outside compressor/fan not coming on. I had someone come out and look at it but according to him he just took the cover off and then pulled some of the wires out and then it started working. Worked for several weeks. Now it stopped working again.

I suspected it was the thermostat low voltage wires coming from the blower unit in the attic to the outside unit. I tested at the indoor blower unit and I read 24v between common and the heat wire... so good voltage going into the tstat wire heading to outdoor unit. I then tested at the end of the tstat wire by the outdoor unit. Again a good 24v reading. Then the tstat wires are wire nutted to some wires that go to a small board in the outdoor unit. I pulled the wire connections there and tested and still had 24v. So it appears that I am getting a good 24v heat call input into the board in the outside unit.

I then tried to test the contactor. I had good high voltage coming into the bottom, but the contactor was not pulled down so no high voltage coming out hence the fan/compressor not running at all. I tested across the low voltage terminals and could not get 24 volts, so i don't believe it was getting the 24 volts needed to engage the contactor. So it appeared to me that the 24v call for heat was good all the way to the small board in the outdoor unit, but it was not putting out 24v to the contactor (I think it is a yellow wire out of the board into the side of the contactor). So I then manually pushed the contactor in to see if the compressor/fan would come on. They both did come on... and the contactor stayed engaged. So i then tested across the low voltage terminals on the contactor and now it reads 24v??? So I'm a bit confused. First there were not 24v across the contactor coil and then I manually pushed it in and now there are 24v across the contactor. It has been running and heating fine the past couple hours.... Not sure what will happen after it reached the heat temp called for and shuts off... no idea if it will turn back on when the temp drops?

I expected that it would kick on when I pushed the contactor in and then when I released it I expected it would relsease the contacts and turn off... but the stayed down and now it has 24 volts???? any idea what is causing this? Or what to check. My suspision is there is something wrong with the small board in the outside unit but nothing looks burned. When the guy came out a few weeks back he said the freon was full so I dont think that is the problem?

 
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Old 12-18-22, 09:06 PM
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If you post the model number of the outdoor unit we may be able to offer better assistance.

O, R, C, W, Y are terminals often found on heat pumps.

What wires are giving you 24 volts outside when a heating demand is present?



 
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Old 12-19-22, 02:06 AM
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There is a low pressure safety switch in the yellow wire between the defrost board and the contactor.
Sounds like you are low on refrigerant charge.
When it gets real cold and the system cools off it will probably not work again.
 
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Old 12-19-22, 12:22 PM
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Pictures

I can't really read the tag on the outside unit for model number, anyone else able to decipher what the model is?
Looks like G???404???, it is very worn out... I would be surprised if refrigerant is low it was checked as okay just a few weeks back... and it heats up air good and was cooling air good. I have a white wire coming from the low voltage thermostat that puts out 24 volts when the heat is turned on... This white wire looks to be going into the board at at WH so when heat is called for it seems to be delivering 24V to WH/W2 but did not cause conctactor to switch on. It ran fine all night and kept the house warm. When i came home from work it was not running again... again just manually pushed in the contactor switch and it stayed down and ran and heated the house very nicely.

I suspect something is wrong with the defrost board but I don't really know how I would be able to test or why after i push the contactor in it then shows 24v across the contactor coil? i don't think the coil is bad, since it is holding the contatctor down and the connections on the contactor are not dirty since the high power is going through. Once its on it works grand, its just sometimes it starts correctly and sometimes it doesn't, but when I manually push the connector in it works.



schematic on outside unit.

I can't read the tag for model number
 
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Old 12-19-22, 04:41 PM
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The white wire supplies power to the electric reheats when the condenser is defrosting.
 
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Old 12-19-22, 10:22 PM
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I would say that the model number is GSH140481AA

Is your thermostat new?

You want 24 volts between Y and C with 1st stage heating demand.

24 volts W to C would be stage 2 if configured for heat pump.
24 volts W to C would be stage 1 if configured for conventional heat ( or the wrong stat is used).



 
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Old 12-20-22, 12:17 PM
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Okay

Okay Thanks for the chart that is helpful. I tested and I am getting 24V between Y and C and it appears to be working sometimes going through several cycles of heating turning off and back on, on its own. When it runs it heats fine, occasionally again the thermostat calls for heat and the contactor doesn't switch to on and I don't mesasure 24v across the terminals, but then I manually push it down and the contactor stays down and it again works like normal and measures 24 volts across terminal. So I believe it is getting 24 volts to the defroster board but not getting 24v to contactor sometimes?

Also yesterday I noticed that the thermostat was set to like 70, indoor temp on thermostat was reading over like 72 or 73 and then the thermostat called for heat and heat came on. Also one time I came home after leaving thermostat set for 70 and the heater wasn't running but the temp was reading 75... makes me wonder about the thermostat now too....

 
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Old 12-20-22, 07:21 PM
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As I've previously mentioned..... there is a LPS (low pressure switch) inline to the contactor.
If you are borderline on charge it may or may not start. It will depend on ambient air.
The warmer the ambient air the higher the low pressure side is the better chance the contactor will close. When it gets real cold... the contactor won't be closing.
 
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Old 12-20-22, 07:25 PM
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Cold coming

Okay well we got this big cold weather coming in the next day or two so I guess we can see if it has trouble starting up again. Any easy way to test if the switch is faulty or if the pressure is low... I'm guessing the pressure test equipment is expensive?
 
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Old 12-20-22, 09:02 PM
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You'd need refrigerant gauges to check the charge. You'd need to call your tech.
 
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Old 12-20-22, 09:49 PM
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You can use a digital meat thermometer to measure the temperature drop across the indoor unit in cool mode.
The outdoor temperature should be above 65 degrees for this test.

The indoor delta tee should be around 18 degrees F. if the indoor temp is &4 degrees or above.
 
 

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