My neighbor had an issue where his a/c unit tripped the breaker. The guy that came out found that the crankcase heater had overheated and the insulation had burned off, making a direct short. He removed the crankcase heater and told him on a typical residential setting, it isn't needed. It's my understanding that while this may be true most of the time, it is designed to protect the compressor from trying to start on a cooler day when there might be liquids on the inlet...compressors don't like to try to compress liquids!

Mine recently started to trip the breaker, but resetting it would start it right back up again. It would run for one or two cycles, then trip the breaker again. I haven't been there when it tripped, just notice that the house is warming up. Since the thing always started right back up again when I reset the breaker, and the only thing running when the compressor isn't is the crankcase heater, I just tried removing those leads and am experimenting to see if it stays on.

If it didn't cool well when it does run, I'd suspect maybe low refrigerant.

I did call a serviceman, but all I got was his answering service, and it's been a day with no callback. May call someone else soon if this doesn't help.

If disconnecting the crankcase heater lets the thing stay on, how critical is it to replace the thing? Also, based on the fact that it always does start up when I reset the breaker and cool (as far as I can tell) in a normal fashion and performance, what else might cause this sort of thing?

The old CB didn't feel quite as strong, and didn't 'click' when resetting like a new one, so I did replace it with the same type just to see if it was change.

The wiring to the outside breaker box is fed by an older 30A circuit. The a/c unit calls for a 15A breaker, and the wiring from that breaker to the unit is 12g with a 15A breaker. With the associated wiring, I could change the breaker to a 20A, and that might have enough margin to let it work, but I'd rather keep it where they called for in the installation manual!?