How do i connect a Commmon wire to Heat Controller Inc air handler?
According to that wiring diagram, C is not available on the terminal block for the thermostat and outdoor unit. You'll have to find it by locating the 24V transformer. According to the wiring diagram, the yellow wire on the transformer would be C. You can verify that it is the correct wire because it should be connected to a couple of relays, and the other wire coming off the transformer should be red and connected to the terminal block for the thermostat.