Compressor trips breaker BEFORE air handler startup

This one is a little different than the typical compressor breaker tripping when starting or running. The breaker will not turn on; it trips instantly even when the air handler is turned off and thus is not asking for the compressor to run. I have replaced the breaker and same thing happens.

To double check the wiring to the compressor, I pulled the outside breaker. This allowed the inside breaker to be turned on without tripping. As soon as the breaker outside is installed, the inside breaker trips. Again this is without the air handler asking for the compressor running. Ditto happens when the air hanlder is calling for the compressor to run.

Ideas please?

Earl

 

Sounds like there is a short between the main panel, and the compressor disconnect, or the disconnect itself is bad. Check the disconnect for any shorts with a VOM, WITH THE BREAKER INSIDE OFF. I can't stress that enough. You don't want to get it with what is more than likely 220-240 volts. it does not feel good. If the disconnect checks out, I would check the wiring from the panel to the disconnect. Then also check past the disconnect into the compressor, again with the breaker off. There will be more responses from the pros as the check this thread.

 

Compressor may be locked up or seized. but if the case there usually will be a time delay before the breaker trips and not instant aneously. If its instantaneously a short or a ground may be your issue as Crazycory pointed out.
With breaker off you can have someone comfortable with dealing with electricity Disconnect the wiring at the compressor and electrically tape them up separate from each other ( besure they dont touch each other or anything else. ( besure to make a diagram document where each of the 3 wires came off of . After taping very well lay them on cardboard or something to insulate them from the unit and each other. Now cycle on power if the breaker doesn't trip and the compressor contactor is pulled in . Then it sounds like you have a bad compressor. If it doesn't then your short or ground is else where.
You can preform this test with your condenser fan motor, If it has a wiring harness with a plug you may want to do it first as its easier to preform.
post back let us know.

 

Thanks for the post but the short cannot be between the panel and the outside breaker since it doesn't trip the inside breaker until the outside breaker is turned to on.

It seem to me that the short must be in the wiring from the outside breaker to the compressor or in the compressor housing or in the compressor relay.

Earl

 

Sound to me like you have a grounded compressor, turn off power and chk compressor terminals to ground.

 

I think I have the same problem.

How do I check the outside disconnect ?

addled in hotlanta

 

so oh well, THANKS !!! never mind.

He said its the compressor. Went thru the breaker replacement, and assorted tests outside at compressor----

Thanks anyway !

 

you can locate the short by looking. Look at the cap, contactor, fan wires up into the motor, remove the compressor plastic cap where the wires go, to see the wire connections....its likely a burnt off wire connection. The guilty culprit will be found with an OHM meter. Check each of the leads to ground...if you have any continuity to ground you have found the problem. You gotta poke around in there...don't be afraid to look here and there and tug on a wire or two. If you think the compressor is bad, confirm it by removing the wires on the compressor and recheck directly off the 3 pins! One lead on a pin connection and the other to ground, if there is any continuity to the compressor, it's toast. Remember not to test it with the overload in place...remove that too.