I have a mobile home coleman furance and it is a split unit, gas furnace and the problem is when I set thermostat , unit not operarte when calling for heat. I have changed transformer and 120 volts to it and 9 on 1 leg and 9 volts on other leg ( transformer is a universal and meets recommendations for unit). Fan operates and heater won't ignite. Fan and heater will work if you turn unit on by the on and off switch on the heater unit itself .I have even went as far as getting the 24 volts from the outside unit and heater still will not start.
