Originally Posted by dr.perry
Thanks to everyone for the replies. I'm going to get on the roof and do some basic troubleshooting. It sounds like it could be a capacitor and I'll get some help with that so I don't do something stupid. :-)
It helps to have a clampmeter with capacitance test feature. My rear unit fan capacitor went bad and did what you described...in air conditioning mode (Jan in Florida...still using A/C)
I would try in air conditioning mode...Just to rule out a reversing valve issue...
Up on the roof...four Phillips head screws remove the cover. The dual start run capacitor can be tricky to find with the same uF values....so, might take a picture of yours to make sure you get the right one. If it is the fan start capacitor...if you have someone to help. ...have them turn the unit on. While you listen for the humming, or notice the fan cage bump. Carefully give the fan a spin with your hand...and see if it doesn't start running. If it does...it's probably just the fan start capacitor...if it doesn't might need a new fan motor.
I keep a spare capacitor with us now. It's an easy repair...but only if you have the part. Seems these things always break on a Sunday, or when nobody within 100 miles has stock of the part.
There are a few different models, so yours may use different values than mine.