Heat Pumps and Electric Heating - Lennox FM21 Control Board

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2old2fit
08-04-07, 08:53 AM
I have a lennox heat Pump with a FM21 control board. The cooling quit working the other day. Nothing at heat pump appears to be running. Fan on furnace is the only thing that runs. What contacts on the control board do I touch (test) to see if it is a circuit issue? Y1 is the 1st Stage Cool/Heat. What other contact do I connect to test Y1?

Ed Imeduc
08-04-07, 06:39 PM
Do you have a high head reset in the unit?? Do you have 24V at the contactor. If you push the contactor down does it run fan and compressor?
R to Y should make the compressor and fan run outdoor's. BUT with out O I think it will run in heat. Might check the defrost control board also