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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8385
Experience:  Furnace, A/C and heat pump specialist.
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My Goodman heat pump is not working. Need troubleshooting

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My Goodman heat pump is not working (The fan and the compressor. No cold and no heat). All the correct 24 volts are coming to the five wires coming from the air handler to the heat pump. There is 24 volts on the yellow wire connected to the fan capacitor. There is no 24 volts on the yellow wire on the defrost control board that leads to the contactor. There is also no 24 volts on the other yellow wire connected to the contactor. The yellow wire that is connected to the air handler goes inside the lower part of the casing (to the pressure switches?). This wire has 24 volts when there is a demand for cold from the thermostat. It seems that the low voltage coming from the thermostat is lost somewhere in the unopened parts of the casing. Do you have an idea about what might have gone wrong? Thank you very much for your trouble!

Make : Goodman 5 tons
Model : SSZ140601AD

Already Tried:
Replaced the White_Rogers programmable thermostat with a Honeywell programmable thermostat. Verified all the connections from the thermostat to the air handler, and from the air handler to the heat pump. Verified the 24 volts on all five wires coming from the air handler to the heat pump. All these low voltages are correct. But the low voltage on the yellow wire is lost somewhere in the system. It goes back to the fan capacitor but not to the lower part of the contactlor.

To start with the yellow wire is a control wire and should not connect to the capacitor. Are you talking about the contactor.? Here is a picture of the capacitor and the contactor

Above is the capacitor
Contactor on a Goodman heat pump
Full Size Image

Above is the contactor

Let me start by asking if you replaced the thermostat trying to fix your problem was the unit operating fine and you just decided to replace the thermostat and then the problem arose after installing the new thermostat?

Customer: replied 6 years ago.

There are three spots for connexion on the capacitor : FAN, C, and HERM. A brown wire and a purple wire are connected to FAN. A red wire is connected to C, and a yellow wire is connected to HERM. It was like that when the heat pump was received.

I had the same problem before I replaced the contactor. I wanted to make sure that the thermostal was good.

The replacement did not solve the problem at all.The 24 volts coming from the thermostat do not reach the defrost control board and the contactor. I am trying to find if some other electrical part is defective.

Customer: replied 6 years ago.

I am trying to find the reason why there is 24 volts coming from the thermostat and no low voltage at all at the contactor. This prevents the contactor from closing to activate the fan and the compressor.

Ok those wires going to the capacitor have nothing to do with the 24 volt circuit. Those are high voltage wires(not in your control circuit at all),So lets don't concentrate on the capacitor. Your control wires should go to the board in the outdoor unit. C,W2,O,Y and R . Lets start at the board with your meter.With thermostat calling for cool, Tell me if you have 24 volts between C and Y where they connect to the board

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Customer: replied 6 years ago.

No. I have nothing at all. Why the heat pump is not working. There is no voltage between the y and the C on the Defrost control board. What would be the next step?

Ok, if you have no 24 volts between common "C" and cooling "Y" at the board, we are loosing it before we get to the outdoor unit. Those control wires come starlight from indoor to the board ,correct?

Have you checked to see if you might have a float switch in the drain inside that might be be breaking the circuit?

Goodman heat pump parts

Customer: replied 6 years ago.

The common C goes from inside to the board in the outdoor unit. The Y from inside goes to a blue and pink wire that goes into the lower part of the casing. I do not see where it goes. The Y on the board is connected to the contactor, but it does not carry any voltage at all.

I have not checked about a float. If you wish, I can do that later and contact you again tomorrow.

Ok, first, can you disconnect the "Y" yellow wire where it comes into the unit (probably a wire nut) and check between the yellow from indoor unit to he "C" at the board?. If you have 24 volts there, it is most likely a pressure switch in the outdoor unit. Can you do that tonight?

Customer: replied 6 years ago.
I will go out and do that now. I will get back to you soon.

I will be here

Customer: replied 6 years ago.

We have the 24 volts there. Then, as you say, the problem is probably with a pressure switch. Is this a part I can replace myself or should I call in a repair person?

Thank you for your help so far!

You will have to call in a tech because the pressure switch is welded into the refrigerant line. Also it is a possibility that the pressure switch is not bad.Your system may be out of freon. I realize it is not that old, but it is not entirely out of the question that you don't have a refrigerant leak somewhere.. Equipment leaks are much more common today with the quality of copper and material .

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