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Richard, Technical Manager
Category: HVAC
Satisfied Customers: 1514
Experience:  27 years of Experience, NATE Certified, professional trainer
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I have a heat pump that is not working. The air handler just

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I have a heat pump that is not working. The air handler just blows cold air and the outside unit does not turn on. I have checked the power with a multimeter and I have 220 coming into the unit. I can defeat the relay by pushing the contacts together and the unit comes on. I'm not sure where to go next. The circuit board is a Goodman B12260-08. I'm not sure what to test on that board to see if it is working. What do you suggest? Thanks, XXXXX XXXXX
Hello, Ok since you have a meter there are several thermostat wires going to the outdoor unit. First see if you have 24 volts going to the relay or contactor you pressed down on. If there is 24 volts you have a failed contactor. If not measure voltage from the yellow thermostat wire to ground for 24 volts. Let me know what you find. Richard
Customer: replied 6 years ago.
Inside the house I measure 24VAC within the thermostat, measured from yellow to common. Outside I measure 6VAC on the thermostat wire, yellow to ground. Thoughts?
Hello could be a broken wire. Measure the voltage at the indoor unit Yellow and common. You either lost the yellow or the common.
Customer: replied 6 years ago.
Well, I have run a wire out the door and to the back of the house and connected the yellow and common (blue) from the thermostat to the back of the heat pump and it still does not come on. However, now I measure 24VAC between the pairs at the heat pump. The relay has a yellow wire that runs to the circuit board on one side and the common runs to the other. I measured less than 24VAC across the relay to ground. What do you think now? Thanks.
Hello if I understand correctly you ran it from the thermostat to the unit? not to the air handler? depending on the board in the air handler you will need to hook that wire up as well. This is kind of the long way. If you go to the air handler on a call for heat do you get power from the yellow to blue ( common?) If you have power there and not outside replace that wire. So lets back track a minute, from the air handler to the outdoor unit how many wires do you have and the color. I understand if it is getting dark and we need to pick up tomorrow. I will only be on for another hour. Richard
Customer: replied 6 years ago.

Thanks for all your help. I will pick this back up tomorrow. I did run a wire straight from the thermostat to the outdoor unit. I was able to put the system on Emergency heat and it is working fine for the moment. I hope to hear some more from you tomorrow. Thanks again.




Hello I will be on most of the day tomorrow. Richard
Customer: replied 6 years ago.
I have checked the connections between the air handler and the outdoor unit. One of them seemed loose and I put the wire nut back on and now I have 24VAC all the way to the outdoor unit between the yellow and blue. Still, the unit does not turn on when a call is made for heat. I guess, since I can cheat the relay and the unit runs and puts out heat that means the run capacitor is OK. What do you suggest now?
Hello now that we have voltage can you check for 24 volts to the coil of the contactor? Check across them then check each to ground. Lets see if we loose our 24 volts or the common
Customer: replied 6 years ago.
I checked the yellow and white wires on each side of the coil under the relay and each measures 12.97VAC to ground, but 0VAC between the two. The thermostat is on, calling for heat at the moment and the air handler is running.
Hello OK we either have a bad defrost board or fallow the yellow and white wires look to see if they go to a pressure or temperature safety switch.
Customer: replied 6 years ago.
I have attached a picture of the only board in the unit. It has two test points and I measure 13VAC to ground on one of them and about 6VAC on the other. Yellow wire goes from this board to the coil on the relay and the white connects to this board also.

Hello give me a few minutes i am going to look for the wire diagram. Richard
Hello Ok I think i found one that is close. On the board you have an R terminal measure for 24 volts from there to Common or Blue. It also showed a low pressure switch from the purple on the board to the same yellow on the contactor terminal. measure for ohm here and make sure it is closed. Let me know
Customer: replied 6 years ago.
Yes. As you said, R to Common is 24VAC and Yellow to Purple shows closed.
Hello recap, we have 24 volts from the R to C(blue)on the board we have 24 volts from the yellow to the blue ( thermostat wires going into unit) and low pressure switch is closed. But no 24 volts from yellow to blue on contactor? The way the diagram that i have shows is if we have 24 volts from Yellow to Blue ( thermostat wires) the only thing in series with this is the low pressure switch and a relay in the board. So if the low pressure switch is closed and we have power from R to C on the board i believe you have a bad board.
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