AC Compressor comes on, but not Condesor cooling fan


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Old 06-01-11, 04:01 AM
C
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Question AC Compressor comes on, but not Condesor cooling fan

I have a Comfort Maker AG036GA1 central air unit (12-15 years old) that we just kicked on for the first time this season. The compressor came on fine, but the big fan, which cools the condenser outside did not. I cycled demand from the thermostat several times and this remained consistent, that is the compressor comes on, but not the fan. I have interrupt service for the air and I have checked both fuses in the box. They both have continuity. I also noticed that the demand from the T-stat seems to require a long time or several changes in demands before the compressor comes on, but again the fan never comes on. I pulled the fan harness and checked continuity via the hot and neutral. The circuit is closed so juice gets through. The fan freely rotates by hand so the bearings are not shot. It looks like there is one big capacitor, which I guess is a dual capacitor because I don't see another one. The electrical diagram shows capacitors for both the compressor and the fan, but I only see one. This unit appears to have a single pole contact relay to get the required power out to the compressor and fan.

My question is whether a bad capacitor could allow the compressor to run, but not the fan. Related to this is whether the single pole contact relay could fail on the fan side, but not on the compressor side? Should I just replace both the capacitor and the relay or can any one tell me if there might be another problem?
 
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Old 06-01-11, 06:08 AM
J
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My question is whether a bad capacitor could allow the compressor to run, but not the fan
Yes, one section of a dual capacitor can fail. Replace it. If that doesn't fix your problem, I'd be looking at the motor next.

Related to this is whether the single pole contact relay could fail on the fan side, but not on the compressor side?
No, fan and compressor are connected to both L1 and L2 as they each require 240 volts. If one pole failed, the compressor (and fan) would not run.
 
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Old 06-01-11, 06:25 AM
C
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Jim,
Thanks for the clarification. You are correct that the fan motor would be next given the fact that I don't have an alternate AC power source to energize it post capacitor.
 
 

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