How do I change the low voltage fuse in a rooftop gas heat unit.
Go to the air handler and look near the transformer for a 3 amp blown fuse. Pull it out and put a new one in (it resembles a fuse used in cars).
SOURCE: Air Conditioner malfunction
Hi, Sounds like you have a short in the control circuit to me. Turn off all power going to the unit. Write down or otherwise mark the wires leaving the control board going to the thermostat. Remove them from the control board. Replace the fuse. Turn power back on and see if the fan still runs. If it does, check and or replace the heat limit switch that brings the fan on during the heat cycle. It may just need adjusted. If the fuse blows, I would think that the control board is probably bad. If it doesn't blow, Remove the thermostat. Leaving all thermostat wires open check them with an Ohm meter. There should be no continuity between them. Twist all the wires together at one end and ohm them again at the other end. You should have complete continuity on all wires. If the wiring checks out, down power the unit. Double check your wire colors and rewire the control board. With all wires open at the thermostat, turn the power back on. Touch the RED wire to the YELLOW wire. The Condensing unit should come on. Touch the RED wire to the GREEN wire. The fan should come on. Touch the RED wire to the WHITE wire. The heat should come on. Down power the unit. Replace the thermostat. Test unit. If the fuse has lasted ok but blows now it is either wired wrong at the Thermostat or the thermostat is bad. I hope I have helped. NOTE: If you can not understand these instructions. Call a licensed Heating / Air conditioning company. kstfas
SOURCE: carrier rooftop unit
figured it out, the problem was return air ducting was capped off, by the construction crew, thanks
SOURCE: Wiring diagram needed RV rooftop coleman
Motor1258,
Thanks for the response, to be more specific, the nine pin connector was damaged, but I was able to connect the wires back to main unit panel. I am ready to hook to the hunter thermostat and do not know which wires to connect to. This is my problem and I do not want to short something out. Hope this helps, I want to get it installed again. Thanks again for caring....Jerry
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