I have a 5 year old unit stopped working Monday replaced a fuse now thermostat working again no aux heat fan works e heat blowing out kind of warm air need to know if it will be OK to run e heat for 4 days until repair man shows up? All electric system any guesses on what went wrong?

Sure use aux. heat as much as needed ,it won`t hurt anything but your power bill
Good luck

I agree but keep in mind something caused that fuse to blow, you could still have a fault. Let the repairman figure this out on site.