Have HVAC Questions? Ask an HVAC Expert for Answers
You are correct. I also commend you for realizing and recognizing the function of door switch. If it becomes too troublesome you can bypass until you get a new switch.
Obviously it is a safety feature for when the bottom door is removed to cut power.
I wish you luck
I apologize...computer troubles...
Clean all the rods and metal components of ignitor with steel wool, reset power and see if cycle improves
Does the other end of the thermocouple look like this?
Good, at least now we know the limit and thermocouple are good. Do you have a meter to check 24v at the gas valve?
you will check for 24 to the gas valve terminal...one meter lead to ground and the other to th on valve.
24v on th with no burner = bad gas valve
sorry for delay...my regular job needed my attention.
Now take the blower door off and tape the switch down again. Find the white wire coming from the thermostat and tell me what it goes to in the furnace.
Great, that is what I wanted....now put red lead to TH and black lead to cabinet while thermostat is calling for heat.
lets leave the black lead on the side metal of the gas valve, no paint and conductive.
Now move the red lead to the white wire coming from stat. Unhook from wire nut and test the wire direct.
go to thermostat and remove top section. Take R wire and W wire and twist together. Metal to metal.
we need to bypass the door switch and make sure power is going to furnace. The red wire should have 24 volts at all times. We are missing power somewhere
Now hook all back up.
so red wire to ground got us 24v. Pull the TH wire from gas valve and measure it to ground the same way. I know we did this before but it was missing last time
Ok now that your familiar with the meter a bit more....
all the thermostat wires come into the furnace. Do they all just connect to other wires or do any mount on a control board?
excellent, the cable with 5 wires comes from thermostat, the cabel with 2 wires goes out to the outdoor ac unit.
The white wire in the cable with 2 wires is know as common. The red takes 24v out to the ac unit.
The white wire in the 5 wire cable is the one that goes to the gas valve on TH right?
Great, thermosta hooked up, heat turned up, power on. Remove TH wire from gas valve. take wire nut off the white wire in the 2 wire cable but leave twisted together.
Red meter lead to TH wire removed from gas valve and black lead to white wire in 2 wire cable.
And not to beat a dead horse...but the white wire from the thermostat goes direct to TH on gas valve?
I understand...check the inline fuse
Take the fuse section out of the equation and have white wire go direct to TH.
Well done. I thank you