Air conditioner quit! :-(

Sep 02, 2008 3 Replies

Just a normal propane fired furnace with an "A" coil and a compressor outside. When the thermostat is set to auto fan and cool the inside circulating fan in the furnace comes on but the neither the outside fan nor the compressor come on. There are two breakers, one in the main breaker panel and then another outside near the compressor. When the both breakers are on I have 220V going to the compressor thus that is not the problem.



When the thermostat is turned to cool there is NO sound at all at the compressor.....not even a a relay closing.



Unfortunately the thermostat is a programmable LUX and it is my opinion this is where the problem is. On the other hand, when set to cool, the inside circulating fan does come on.



Your comments and suggestions would be welcome.



Don


(Carefully) check the voltage across the contactor (relay) coil. When the thermostat is calling for A/C, it should be around 24 volts AC. If it is, and the relay isn't activating, then the relay is bad. Otherwise, there's a problem somewhere in the control circuit -- it could be the thermostat itself or the wiring between it and the outside unit (or, if there are additional control devices between the two, like a short-cycle control, it could be a problem in those).

Well, it sounds like time for some electrical troubleshooting. Or, you could call a HVAC tech and pay him (her) to do some electrical troubleshooting.

What's your skill level?

Just check to make sure someone didn't cut the 24 volt control wiring outside with a weed wacker. That happens alot.

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