Why won't my furnace work? The pilot is lit, I can hear the thermostat click when I raise & lower the temp...

Question

if I turn the fan to on it will blow. The main burner is not lighting, any thoughts?

I don't think it's the thermocouple because when I disconnect it the pilot will go out so I think it is sending out it's signal saying the pilot it lit.

Answer 1

You need a new thermocoupler. You can usually buy them at a hardware store so you need to turn off the heater and let the pilot to go out. Then remove that metal rod that is over the pilot light and go down to hardware store and have it matched up. Install new thermocoupler and lit pilot.

Answer 2

It sounds like the thermocouple is gone. How old is the unit. These are simple to replace and can be bought at the Big Box stores. They come in two or three different lenghts. Take a look inside and look for a metal encased wire from the pilot light to the gas valve . make sure the thermocouple is touching the flame . When heated up they produce mili-volts of electricity to open the main valve. Make sure the control on the thermostat if there are any are on heat and not a/c. Also check that it is on auto and not the on setting

Answer 3

This problem is indicating that the computer/electronics that control the burner gas valve is not functioning properly. The fact that you power off and back on to make it work leads me to believe that is component is the problem. If you have some experience with electronic circuit board replacement, you can most likely find and purchase the circuit board online and install it yourself. However, this is a bit risky if you don't have the experience necessary to test, troubleshoot and resolve these types of electo-mechanical issues. I would suggest you call a trusted AC/Heat service company. If you feel that are two high, get another company to come out and give a second opinion. You can expect to pay about $75 for the diagnostic call-out, $75 for repair trip and anywhere from $100 to $500 for the circuit board if it needs replacing. Good luck and I hope this helps.

Answer 4

Did you check to see if you have power to the furnace. the pilot will light and stay lite without power to the furnace but the gas valve will not open without power. it also may have a fuse on the control board. Now lets check for 24 volts. there are 5 or 6 little screws labeled Y W R G B & c you should have 24 volts from C to W with t-stat calling for heat. I can explain in more depth at [e-mail]

Answer 5

check the 2 wires going to the control solenoid on the gas valve. If you get no continuity then no gas will come out. This does happen from time to time. In the old days you could just buy the solenoid. But now you gotta get the whole valve. If that is ok then check the thermodisc right there beside the valve. One side of it hooks to that solenoid. If you can see the red button when looking side to side then it has popped up and needs to be reset but wait? why did it pop up? because it got too hot in that area. Be sure to check for stopped up pipes and cobwebs or rusty half blocked burners that cause flame roll out etc.

Answer 6

the solenoid might be stuck closed if so it might need a new one because this is what allows gas to the main burners also find the reset button and try to reset it it should be a red button on the unit somewhere turn your thermostat down to zero and press it then turn the thermostat back on with the fan

Answer 7

Could be a loose or broken wire, or a bad gas valve.
If you had a bad thermocouple, your pilot would not be on.

Answer 8

not the thermocouple for sure, if it was there would be no pilot. sounds like a problem in the low voltage wiring.

Answer 9

Personally I wouldn't dink around with a do it yourself fix with a furnace. Call a pro in and have it checked out. If for nothing else, your safety is at question.

Answer 10

Logsdodl is right....the thermocouple is nfg.
They stock them at Home Depot and all the hardware supply joints.