I have a sears 600 series natural gas furnace with a pilot that has to be lit manually. When I light the pilot everything works fine until the burners ignite, then it will run anywhere from 10 seconds to a few minutes until I hear a "click" come from the gas valve and the burners and pilot both go out. If I don't light the burners then the pilot will stay lit. It's only when the burners come on that the gas turns itself off. The blower isin't affecting it because sometimes the gas turns off before the blower comes on and sometimes after. Any help would be appreciated.

 

Is there alot of snow on your gas meter vent? Or is the gas **** not open all the way? I asked this backwards. Do the flames get smaller before they go out? Or just the pilot get smaller? Or everything looks good and they just go out?

 

Try cleaning your pilot. You can tap on it and see if the flame gets bigger.

 

You Nat gas or LP how old is the T/C there . Like said clean the pilot Venturi

 

The pilot isin't the problem. Like I said if I just light the pilot and leave the furnace off it stays on just fine. But when the burners kick on the gas turns off. It's almost like some sort of safety switch is turning the gas off. I'll hear the click in the gas valve and then the flames go out all at once. Whatever that click is it's turning off the gas.

 

I don't know if a pilot light furnace has a flame sensor for the main burner or not. It sure sounds like what a bad flame sensor would do. Main burners light, flame senor can't read the flame and shuts down the whole system for safety.

 

Do you have 2 wires under the thermalcouple going to the front of the heat exchangers? And are the heat exchanger hot? No? You have gas supply, thermalcouple( low pilot flame) or bad gas valve problem.

 

If there is a flame sensor I don't know what it looks like or where it's located...I sure don't see anything that looks like it would be a sensor.

 

Clean the pilot venturi and the burners. Then see what it does