Have HVAC Questions? Ask an HVAC Expert for Answers
Hello, have you checked the 3 amp fuse on the control board in the furnace?
Just get to the board pull the fuse off the board and check it, it may just be burned out causing the whole issue. It should be a slot fuse right on the board.
Yeah no problem
Ok does the fan come on when selecting FAN ON at the thermostat?
Are any lights flashing on the board at all?
Ok can you check the power to the furnace or the out of the transformer it appears you lost your low voltage power to the board. Can you upload a picture of the wiring diagram here?
You need a volt meter and check at the thermostat terminals, if you have a pic of the schematic on it I can tell you where to test.
Ok you have a limit switch in line with the fuse on the transformer. Look around the unit for a resettable limit switch there should be one around the unit that is tripped
No it should be close by and have RED wires to it.
Yes push the button on the switches and see if it clicks int and you get a light on the control board.
Can you follow the RED wire out of the fuse to the limit switch?
If you see the large 9 pin molex plug on the board follow the red wire to that limit switch that should be the one...connect the wires to it together and see if the unit comes on.
Also confirm you have 120 volts to the furnace
Can you get to the junction box where the wiring goes to the unit? If so test across the black and white wires to it for 120 volts AC
Ok do you have the door switch depressed when testing this?
Hey I am going offline soon we can pick this up again tomorrow if you want,
You need the door panel switch in and check across pins 3 and 6 on that nine pin molex plug for 24 volts AC it should be the RED and Black wires there, look at the diagram and find the 3 and 6 pins on the diagram.
If you do not have 24 volts there you may have a bad transformer if you have bypassed that limit switch.
OK just let me know if you still need help