Unit: Trane 5 ton heat pump, 12 years old.
Our AC company came out last week for the annual "Fall Check up". During the check up, the tech turned off the outside unit to check wires, etc. When he flipped off the main switch at the wall, the unit let out a squeel for about 5 seconds as the unit shut down. He continued his check, closed up the unit, then left.
The next day, we attempted to turn on the AC. The indoor blower worked, but air was warm. The outdoor unit was not running, and the main house AC breaker had tripped. I tried flipping it back multiple times, but it still tripped. I tried with the thermostat on & off. The AC company sent out a different tech the next day who said the "compressor was grounded" and needed to be replaced. He strongly recommended a full unit replacement at $4,300.
Is it possible something was done during the maintenance call that could have caused this? What causes a compressor to "ground out", and can it be fixed without full replacement of the compressor or unit? This whole ordeal seems fishy since it was working fine before the "check up".

 

A 12 year old unit isn't new, but it isn't ancient yet either. And if it was working before he came and wasn't after its really hard to argue that it died for some other reason than the tech did it. He should have fully tested the unit before leaving, if he did not you did not get what you paid for in your service contract. You were there. Did he fire it up and check it before he left??? There is no way to know for certain what killed your unit, however given the coincidence I think it is reasonable to ask them to replace the unit at their cost. Get an estimate from another a/c rep for a similar size/SEER efficiency unit. I would want 30% below whatever was the lowest of the two quotes (the one you already have plus the one you will get from another rep). If he disagrees find a new installer as your current one would now seem less than admirable in my mind. Also ask for a refund of the unused portion of your service contract if the is a pre pay deal and report him to the BBB if he refuses.

>>What causes a compressor to "ground out", and can it be fixed without full replacement of the compressor or unit?

All that is meant by grounding out is that the compressor is dead. It has internally short circuited. Compressors are unrepairable and not cheap to replace. You could replace just your compressor, however it is not worth it based on the age of your unit and the fact that much higher efficiency models are now available then when yours was installed.

>>I tried flipping it back multiple times, but it still tripped.

In the future do not do this. If a breaker has tripped it tripped for a reason. Its ok to reset it once if you are unsure why it tripped, but beyond that you need to determine why it is tripping and clear the fault before resetting it. In any event I doubt you caused any additional damage since the compressor was most likely dead before you did anything. Continually resetting a tripped breaker can damage equipment, house wiring, the breaker, and the breaker switchboard. -doug

 

Unfortunately as Doug pointed out flipping the breaker on and off could easily have damaged the compressor.

Interesting comment:
I am not sure why folks expect that once a tradesman touches a piece of equipment they become responsible for any future or other mechanical problems?

A subject close to home:
I had repaired a rooftop cooling unit two days ago and when done I performed some basic maintenance on an identical unit beside the first which hadn't had a problem for a long time.
Last night I got a call to say the second unit was not working.
Seems the diaphragm on the valve I closed then opened failed and all the refrigerant leaked out............Should I be responsible to replace the valve and refrigerant at no cost???

 

Great feedback Doug, thanks. I'm calling my ac company tomorrow to speak with a manager about this incident, because no... the tech never checked the system to ensure it came back on. He simply closed the unit up, turned back on the main switch and left. I have a couple other AC companies coming out this week for quotes on new units as well.

 

Did the tech smell like a whiskey bottle per chance?

 

Yes, but the fact that it tripped out the first time he fired up the system after the tech left leads me to believe the compressor was already dead before the homeowner did anything (in this case).

I have worked as an electrician so I am not blind to the fact that we, tradesmen, are blamed for problems we had nothing to do with. Again, in this particular case I think the a/c maintenance guy had the responsibility to fully test the unit before leaving. Especially since this was a so called check up.

In your example, you touched it last so you broke it. (Sorry, but you obviously know the game). If it were me I would offer to repair it for the replacement part cost only or if it was going to be a labor intensive repair at least offer a discount. How often does something like this happen, really? Not often. Sadly we don't make money on every job. Sometimes we don't even break even. But a happy customer will call you back next time and will recommend you to a friend/neighbor/etc which is how you will make the money back.

-Doug