I have a Rheem A/C 4 ton unit that works fine in the A/C mode but when I put on the heat, which is only a couple times a year living in Florida, it blows one of the 35 amp fuses in the main, and the motor gets extremely hot. So hot you can't touch it. I feel the motor might be going bad. I put 60 amp fuses it the mians and ran the heat for about 2 hours and the motor shut off on its own without reaching the preset temp. on the thrmostat, possiablly due to the over heated contact strips in the motor. I monitered the # 8 gauge cu. wire feeding the unit from heating up and it was cool to the touch about a 1/4" from each connection, so I'm pretty certain there is not a fault on the wires. Seeking possible problems if not the motor.

Putting 60 Amp fuses in is a good way to burn down your house! #8 as romex, as I would suppose is what you have, is rated to 40 Amps. You are obviously pulling more than 35. Make sure the cooling vent openings in the motor are clean of debris, spider webs, dirt dauber mud etc, the motor is oiled and turns freely. The thermal overload switch is working, fortunately or you would have burned out the windings by now.

Have you talked to your dealer? Upon purchasing major appliances like an air conditioner or hot tub or spa (http://www.buyerzone.com/residential/hot-tubs/rfq-hot-tubs/), it's crucial that you set up some type of maintenance plane. Your dealer should have offered it to you.