Originally Posted by JASPER2008
I'm having a problem with my furnace and I hope someone will have some advice. I have a forced air furnace (LPgas) with an electronic continuous try pilot. My problem started about a month ago the furnace would not stay lit after the burners started. I replaced the pilot sensor and sparker and all seemed fine. But now the problem is: the thermastat calls for heat, the pilot lights, the burn runs for about 2-3 minutes (heats up the chamber), blower turns on and them immediately everything shuts off. It will not relight or restart unless the unit is turned off at the thermastat or at the breaker. Then it will once again go through the same cycle never actually heating anything. The blower works independantly when it is turned on. (no heat or cool just the blower).... I'm looking for some advice as to what may be causing the problem?? Any ideas or solutions???
will the heat stay on if the fan is left in the "on"position if you know how to diagnose a circuit with a meter check the limit circuit the one to suspect first would be the one on the back wall of the furnace behind the gas valve its got 2 wires (usually with spade clips) its low voltage you could just try putting those two wires in contact with each other(jumping thenm togeather) see if it stays on if so that limit is weak and needs replacement make sure filters are clean,although thats the first thing people do when the furnace dosent work,usually.