I think I have a relay or thermostat problem.


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Old 08-03-09, 01:06 PM
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I think I have a relay or thermostat problem.

I need assistance with an AC problem. The heat consistantly pumps, even when the cooling set pt is set. The unit in the back comes on and I believe I hear the blower. Also the copper tube gets cold. I also here a constant clicking noise at the unit. I believe this is the relay. How should I proceed with fixing my unit?
 
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Old 08-04-09, 04:13 AM
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1. Is the unit a heat pump?
2. Do you feel air coming out of the vents?
3. Did this just start all of a sudden or has it been slowly getting worse?
4. Did you replace your stat recently?
 
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Old 08-04-09, 10:18 AM
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If you have an issue with the unit constantly pumping, the contacts on the outdoor unit are made.(closed) A simple test would be to check for 24v across the coil of the contactor when the compressor is pumping and it is not supposed to. If you have 24v, the thermostat is either not programmed right, or its bad, or the low voltage wire is bad going from the thermostat to the outdoor unit.
If you do not have 24v present across the coil, then the contacts on the contactor are welded, and you need to shut down the unit at the disconnect and verify that you have no power. The contactor would need to be replaced at that point...not repairable. Plus, its usually only $20.
The clicking noise could be a rattle in the unit, or a loose wire connection in the unit that connects to a set of contacts. When the unit runs, it vibrates and shakes the wires, causing the connection to make (close) and break (open).
Not enough specific info to properly diagnose, like dun11 implied.
 
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Old 08-04-09, 10:30 AM
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Also, If the thermostat had been replaced, like dun11 asked, with a honeywell vp8000, lets say, then it could have been set up wrong. the thermostat has to be told whether the unit is conventional or heat pump, and whether to energize the reversing valve on heating or cooling.
If no new thermostat, and no bad contactor, look at the reversing valve coil and its wiring. Is it being energized/de-energized properly? Usually on a heat pump the unit fails to heat...so if the reversing valve coil goes out, or doesn't get voltage, the unit will be in heat mode.
So the problem could be as simple as the rev. valve wire wire has a bad connection.
Again, that"s only if it's a heat pump.
Hope this helps, -MJ.
 
 

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