Condenser Info

Today, 12:24 PM

Well, this has only happened twice now.

This is a Lennox split heatpump system. 12HPB48-9P.
The unit was running, then the condenser unit fan stopped running (unit was heating) and I had cool mist coming out of the unit. It looked weird. Compressor still running.
I noticed it changed sound so I went outside and witnessed the event.

I took the side cover off and inspected for burned wires associated with the fan, and it's all immaculate. Pushed in the contactor and it all started up normally. There is a separate fan relay on the pcb.

I talked to a guy I know who is a licensed HVAC guy and he said fan motor and associated wiring, or the contactor. No kidding, exactly what I had looked at. He said he had never had a start/run capacitor work then not work then work again, so that's probably not it. I would agree with that. I am not in the business but I have done lots of electrical work, I am an engineer.

This is a newer unit, maybe 5 or 6 years old and in sunny southern California the unit isn't exposed to bad weather. So it all looks immaculate. The fan blades, motor associated wiring, gorgeous. Bright and shiny. No sign of heating from a bad connection.

So no problem found.
Until this morning. Same thing happened. Second time AFAICT.

I could just throw a fan motor at it and see if that solves the problem but since it only seems to fail at 3 or 4 month intervals my ability to troubleshoot is impaired.

Lennox is complicated, I know. The stuff of engineers. In some respects pointlessly complicated. Extra doo dads. Heh.

Any bright ideas? I'm down to the fan motor and the fan relay on the PCB. I guess the motor is more likely, I have had fan relays fail and often there is sign of bad connection. I saw green flames 6" long from one before!

Today, 12:31 PM

Quote:

Originally Posted by Bruiser

I am an engineer.

Locomotive?

Today, 12:37 PM

Quote:

Originally Posted by Bruiser

Well, this has only happened twice now.

This is a Lennox split heatpump system. 12HPB48-9P.
The unit was running, then the condenser unit fan stopped running (unit was heating) and I had cool mist coming out of the unit. It looked weird. Compressor still running.
I noticed it changed sound so I went outside and witnessed the event.

Sounds like normal defrost mode.

Today, 12:53 PM

Defrost mode, maybe. Should the fan stop in defrost mode?

But afaict this has just started- the change in sound was so nontypical that I noticed it immediately. I am watching it for now.

I took the side cover off and pushed the contactor, and it all started up fine just now.

So I dunno.

Today, 01:31 PM

Quote:

Originally Posted by Bruiser

Defrost mode, maybe. Should the fan stop in defrost mode?

But afaict this has just started- the change in sound was so nontypical that I noticed it immediately. I am watching it for now.

I took the side cover off and pushed the contactor, and it all started up fine just now.

So I dunno.

Yes the fan must stop during defrost.

Lennox heat pumps are no more complicated than any other brand.

I have had these calls quite often. After several years the owner notices defrost for the first time.

If you are still worried find a skilled tech (won't be cheap and not every company has one, choose carefully) to diagnose it, rather than randomly throwing parts at it.