I have a Trane XE80 HVAC unit in my home. Fan will not turn on at all. Blower is free, spins easily.

Could this be a capacitor, fuse trouble or controller issue. (I hope not the controller)
any ideas what I can check.

Usually if the capacitor is defective the motor will try and start or not run to capacity. Check capacitor.
As long as you have power to the unit a circuit breaker or main fuse should not be a problem.
There should be a circuit board in the unit many times they are fused and you can check for that.
If the unit has a added stand alone fan relay you can check that.
Last
It is possible that the fan motor is defective. See if power is being supplied to the motor when the unit is calling for it to be running.

Air-conditioning unit on the outside won't come on - fan inside works fine. What would cause the air-conditioning unit not to come on. Thank you.