Defrost Board


Old 02-12-14, 04:33 PM
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Defrost Board

Will a defrost board going bad cause your aux heat and blower to run? I have a Amana package heat pump that when thermostat is not calling for heat, the aux heat and blower will stay on until I flip the breaker inside of the house. The outside fan or compressor isn't running when this happens. This doesn't happen constantly, maybe once or twice a day . Sequencer has been replaced and inside thermostat. If board is going bad how do I check?
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Old 02-12-14, 06:25 PM
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If the unit goes into defrost the compressor should remain running, the outside fan should shut off and the board should tell the aux heat to come on. When the heat comes on the blower should come on with it.

Now you are saying that the aux heat and blower are staying on all the time. That could be caused by a relay stuck on at the defrost board.

The pros should stop by and add their opinions on this problem and a model number of the package system would be most helpful.
Old 02-12-14, 08:50 PM
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You could separate the W (might be D on some Rheem/Ruud units) wire from the outdoor unit and measure the wire then the terminal to C for 24 volt AC (outside) when this problem occurs. ( separating W from the wire (outside) might also prove this if you do not have a meter).
Old 02-15-14, 10:30 AM
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The unit goes into defrost fine and works fine. It is just occasionally that the heat and blower will stay on. I don't know if it is during the defrost cycle or not. Last time it done this I checked the wires where the inside thermostat is hooked up in heat pump and I was getting 24v on W1 and W2 (these have a jumper connecting the two). A maintenance guy at work told me if I was getting 24v on any of these wires when the thermostat wasn't calling for heat that the indoor thermostat was bad. Replaced thermostat but it is still doing it. I am getting a signal from somewhere to cut the heat on (staying on until flipping breaker to cut off). I didn't know where else I could get a signal from except the defrost board.
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