How do you troubleshoot a heater blower that is not working on a 1985 Jeep CJ7?

Check the fuse first (owners manual has a fuse box diagram) or might be on fuse box. If o/k then:

Unplug the motor and check for power(test light or multimeter) going to the motor. If you have power (key on engine off) change the motor. If no power check the resistor and then the wiring back to the switches/relays.