Carrier AC Compressor and Fan not starting

548 Views 10 Replies 4 Participants Last post by jhunolt, May 28, 2020

jhunolt

Discussion Starter · May 27, 2020

Hi All,

I have a Carrier 38CK-036-340 AC from 2001. A month or so ago I uncovered it and ran it for about 15 minutes with no issues, the temp then was in the upper 70's.

Yesterday we had the first day just short of 90 and today and tomorrow are expected to be over 100.

I turned the AC on yesterday and the in house fan started running but the compressor outside never started. I could hear a humming sound so I immediately turned things back off.

I took the cover off and the contactor is closing, that was most of the humming sound, but neither the fan or the compressor are starting. There is no dirt built up, fan turns freely. There is no obvious leakage from the capacitor.

My question is whether a bad contactor or capacitor, or even a bad compressor would also keep the fan from starting?

Given the costs I am thinking of ordering the contactor and capacitor and just replacing both.

Any insight appreciated.

Thanks,

Jon

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surferdude2

· #2 · May 27, 2020

Check to see if you have voltage at the disconnect switch and if it's getting to the contactor terminals. Your breaker may be turned off at the panel. If it's tripped off from an overload, you have a more serious problem that will require further diagnosis.

The contactor humming is normal and it gets power from a different source than the compressor and fan.

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surferdude2

· #6 · May 27, 2020

Check for voltage on the contactor at both input and output sides.

Perhaps the compressor is running?? Does the smaller copper line running to the compressor get hot?? (normal if it's running). If so, and the fan isn't running, the fan motor or capacitor may have failed??

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surferdude2

· #8 · May 27, 2020

Yep, sounds like the fan capacitor has failed. Perhaps along with the compressor capacitor if it's a dual type.

Hopefully the fan motor is still OK... it may have been damaged as well.

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surferdude2

· #10 · May 27, 2020

Don't traumatize it any further. The compressor capacitor has also likely failed along with the fan capacitor. It's usually a dual capacitor unit that serves both.

Get a new capacitor and hope that the fan and compressor haven't been damaged.

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