I woke up this am to find one of my 11yr old heat pumps blowing cold air and lagging behind one degree. It must have just broke within the last 45 minutes since it was about 28 outside. The outdoor fan was not running but the compressor was. I switched it to aux heat until I got home this afternoon.
The unit has a remote temp sensor that is wired to the indoor t-stat so the aux heat can be locked out when the outside temp is higher than the desired preset point (set at 35 degrees). The sensor was being affected by the excess heat coming off the broken unit so the aux heat was not running until I switched it on manually. Maybe its a bad idea to have the sensor mounted to the cabinet like they recommend. :idea:
This afternoon I went out to look at it and decided it was going to be easier to just replace a few parts rather than sit out there in the cold and troubleshoot it. I have a spare capacitor, spare blower motor and spare control board since I have two identical units. Since the motor is harder to replace I tried the cap and board first and found that the problem was the control board. I put the bad one back in and it worked for awhile then started doing other weird things in addition to the fan not working. :roll:
They call these “defrost boards” but they actually control the entire unit.
Its all working good now with the new board so then I decided to look online for another spare $123 board :shock: and found a used one on ebay for $35 including shipping :mrgreen: