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IBuiltPools 01-14-2010 01:51 PM

Heat Pump Control Wiring Questions
 
I've got a Comfortmaker heat pump system from 1986. This unusually cold Florida winter has exposed some problems with it. I have noticed over the years that it has blown cold air in the house while defrosting but it's never really been an issue. Now with this sub freezing weather it's going into defrost while running and cools the house. After the cycle it goes back to heat but now has to overcome that extra degree or two it's cooled the house and we enter a never ending cycle of a cold house. After doing some research online I have found that it's been repaired and rewired by some people that perhaps don't know what they're doing. I have installed a Rite Temp programmable that is wired correctly.
For one, the compressor fan has been replaced and is wired directly to the compressor relay.
I understand that when the defrost timer puts out a signal the compressor fan should shut down and the air handler should shut off, or turn the heat strips on.
There are only four wires to the compressor. Common/AC, Compressor, and Change Over. There are two unused wires in the compressor which are labeled X, and W1. I'm guessing that the W1 should be connected to the aux heat and would be the signal from the defrost timer. What is the X? I cannot find any reference for it online.
Would it be safe to add a relay to turn off the air handler when the defrost timer activates? I'm also considering changing the timer to 90 from 60 minutes.

beenthere 01-14-2010 02:29 PM

No. Don't shut the air handler off. It will take longer to defrost. And could freeze up the indoor coil. The heat pump needs the heat of the house to defrost the outdoor coil.

Reconnect the outdoor fan motor wires to the defrost board. And then check that the defrost board actually shuts the fan off. And that it actually runs the fan.

X should be a trouble indicator light. Not sure on that unit though.

But, W1 should be wired to bring on your strip heaters if you have any.

IBuiltPools 01-14-2010 02:38 PM

Okay. I'm looking into the air handler right now. The relay for the strips is getting power (when I send it) but not closing. I'm looking online for a replacement and it is described as part number 15sh2 SWITCH ELECRIC HEAT SEQUENCER made by Carrier. What does the sequencer part mean? Is this not a simple 2 pole relay?

beenthere 01-14-2010 02:45 PM

A sequencer is a timed closing device. May take 1 or 2 minutes the first time.


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