My Ac/ furnace fan will not come on. I found a dead short in the power supply, repaired it and the fan worked great. Now it has quit again. I turn it on and hear a buzzing sound and the motor heats up then a relay turns it off. It cools and tries again. The moter is not old and turns freely, as does the fan. What could be the problem?

Try a new capacitor. If that does not get it your motor is probably bad. Motors are not supposed to run to hot to touch unless something is wrong.

What does the capacitor look like and where do I find it?

It is in the condensing (outdoor) unit. It will be round or oval. Replace with same size that is in it now.

The A/C compressor works fine. It is the blower in the furnace that will not start. It gets hot and makes a buzzing sound then a breaker or relay shuts it off. I fixed a dead short a week ago. All was good, but now it has stopped again. The furnace is old(mid 70s), but the fan is good and blower is about 2 years old. Could the short ruined the capacitor or motor on the furnace?

Inside the furnace, the capacitor will more than likely be on the blower casing. It will be round or oval with 2 leads Brown attached to it. If the blower motor is getting very hot it is shutting off on it's internal overload and will need to be replaced. I replaced one last week that was only 30 days old.

Okay Thanks! I guess the short did this? Should I try the capacitor also?

Try a capacitor first the when and if that does not work change the motor. Remember the capacitor has to be rated for the motor it goes on.

Check the fuse at circuit board first

Thanks Guys! I will keep you posted!