I have an outdoors central air unit, but the blower is inside my home.

At this moment, neither the compressor or fan shows any signs of getting power. The compressor is not making any noise and the fan is as motionless as the wind is on this hot day. One thing that makes it harder for me to diagnose this problem is that one day the unit produces cool air, the next day nothing but hot air.

I checked the capacitor and it is clean and does not have any bulges. Could the capacitor still produce intermittent problems?

I checked the coil and there is not any freezing noticeable.

I visually checked the thermostat electrical board and contacts. All looks good.
Note: the thermostat does cause the inside blower to come though.

Posting this is the last resort before calling a serviceman...

Thanks
BTR

Quote:

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Originally Posted by trentlove

I have an outdoors central air unit, but the blower is inside my home.

At this moment, neither the compressor or fan shows any signs of getting power. The compressor is not making any noise and the fan is as motionless as the wind is on this hot day. One thing that makes it harder for me to diagnose this problem is that one day the unit produces cool air, the next day nothing but hot air.

I checked the capacitor and it is clean and does not have any bulges. Could the capacitor still produce intermittent problems?

I checked the coil and there is not any freezing noticeable.

I visually checked the thermostat electrical board and contacts. All looks good.
Note: the thermostat does cause the inside blower to come though.

Posting this is the last resort before calling a serviceman...

Thanks
BTR

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If the starter/contactor is pulled in by the 24 volt supply then you should have 220/240 volts going to the fan motor and the compressor circuit if the 220/240 volts is available to the unit. The contactor starter looks something like these pics. Also 24 volts goes to separate different terminals that feed the coil and the 24 volts is supposed to be there to pull in the contactor to make the circuit so the outdoor unit runs.

I knocked the dust off my multimeter to test the CONTACTOR and turned the air conditioning system back on. This time the compressor and fan came on and the house was cooled as always. I did not get to test the CONTACTOR.

Because of this, I am thinking to eliminate the compressor, fan motor, and the contactor as possible culprits.

Is it possible for the thermostat to work sometimes and then not work at other times? One day the system works and then the next it doesn't and then the next it does?

Quote:

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Originally Posted by trentlove

I knocked the dust off of my multimeter to test the CONTACTOR and turned the air conditioning system back on. This time the compressor and fan came on and the house was cooled as always. I did not get to test the CONTACTOR.

Because of this, I am thinking to eliminate the compressor, fan motor, and the contactor as possible culprits.

Is it possible for the thermostat to work sometimes and then not work at other times? One day the system works and then the next it doesn't and then the next it does?

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Anything is possible BUT when a system is not working is the best time to track down the problem. Could be a loose wire etc.