My research brought me here and after I read the other reviews for this problem with
this unit, I decided to roll the dice and ordered the PC control board. Make sure you
get the right one. There's another one for the display panel/remote control. Not that one.
I had already had the unit apart once, thinking it might help to give it a good cleaning before
asking it to get us through another Arizona summer. This allowed me to take out a couple
more screws and do a quick visual inspection of the original PC unit that was now 3 years old.
Of course, this revealed nothing, but it did give me the confidence to go forward with replacement. Ordered the part, it came in two days later. Two hours later I had the system
up and running like new. Hope it lasts. Heavy unit to deal with, but this job not too bad.