A/C Breaker Trips


Old 06-06-08, 06:58 AM
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A/C Breaker Trips

My reliable Trane A/C unit stopped working this week.
Trane TTX0360100A0 - Mfg 1993
The Circuit breaker on the A/C keeps tripping.
I took the covers off of the outdoor unit, and cleaned it up.
When I turn on the breaker I see the following:

Compressor shakes/spins for 1-2 seconds, then waits for ~3 minutes, and does it again. This will repeat for about 15 minutes. The fan never turns on.

When the thermostat is turned on, I see the contactor relay close, and I see a spark when it closes. Then the breaker blows and nothing happens.

It appears that the compressor is not seized. The fan spins freely, and I checked it with an Ohm meter, and it registered about 560 ohms.
A visual inspection of the electronics shows no obvious loose or burned wires or capacitors.

I assume that there is a short somewhere.
How do I track it down.
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Old 06-07-08, 10:10 AM
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Sounds like the compressor took a dump. Disconnect power and pull the cover off the compressor terminal, pull the wires off and ohm between the three posts most likely you will find that the short that you are searching for is inside your compressor. On a good compressor you should be reading around 5 to 10 ohms between the posts let us know what you have.
Old 06-08-08, 08:03 PM
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I measured the compressor with an ohm meter, and it reads ~ 23 ohms between the leads.
When I push in the breaker, I can hear the compressor turn briefly, but the fan does not start.
When I turn on the thermostat, I see the contactor connect, then a blue spark, and the breaker blows.
I am beginning to think that the fan motor or one of the capacitors is bad.

From what is happening, I assume that I have a short in the circuit somewhere. Any help on what to check first ?

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