Carrier APU unit it will turn on but no heat or A/C works, no power in the outlet works. Checked fuse is working. I disconnect battery to try to reset it .No luck. Any ideas will be helpful Ty.

I know absolutely nothing about this. But here is a Operations and Maintenance manual for you. Hope it helps. Note page A5 (Fuse Locations) there is fuse at the generator and two more in the unit itself, one for the unit and one for the outlet.
I guess depending on model there are also thermal fuses and apparently on some models a small DC fuse.
Take note on page A7 OUTPUTS. If high heat is on outlet is turned off.

www.impcotechnologies.com/pdf/manuals/30-864-81E.PDF