Indoor unit is running but outdoor heat pump is not

by Timothy
(Beaufort, SC)

Lennox 12HPB60:
It's hot today! With the AC set at 79 (at 2 zones), I noticed the temperature inside climbing, but the upstairs heat exchanger fan was running. The compressor outside, however, was not running. I turned the AC off at the thermostats and the fan kept running. Then I flipped off the breakers on both the compressor and the heat exchanger, hoping to reset the system (this seemed to work one other time). When I flipped the breakers back on, even with the thermostats in the off position, the heat exchanger fan kicked on. Still no compressor, though. After a few more attempts, the fan did stay off.

Out of curiosity I asked my wife to flip the breakers on - first the compressor then the exchanger - while I stood next to the compressor. When she flipped on the compressor, nothing happened, but then she flipped on the exchanger, I heard a click in the compressor unit. Then I did it the other way. After turning them both off, I had her flip on first the exchanger (the fan came on inside). Nothing at the compressor. Then she flip on the compressor. Again I heard the click.

Electricity is flowing to the compressor/condenser unit, but it's not running. The fan free spins on top of the unit if I manually turn it (with a stick). Is this enough information to help you help me troubleshoot this beast? Thank you for your time.

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Sep 07, 2013
A few ideas for your Lennox heat pump
by: Anonymous

Troubleshooting remotely is a little difficult but here's a few ideas. Your circuit breaker test shows that power is getting to the outdoor unit but not to the compressor. So here are a few common reasons for this:

- faulty wiring even though work wasn't performed sometimes terminals slowly break loose

- bad contactor. The click your are hearing is probably the contactor closing or trying to close.

- bad start capacitor. This may be the most likely culprit. Since you are hearing the contactor close power isn't getting past th capacitor.

There are sometimes other reasons for power not getting to the compressor. But these are a few thoughts....

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