I have a 10 year old Carrier gas furnace that keeps shutting off every 24-48 hrs. First I thought it might be the flare sensor but then I checked the bottom door and it wasn't completely closed. I opened it and then closed it again properly and the furnace started running just fine. Then after a day or two, I noticed the same thing happening again – furnace trying to come on but burners would shut off after a few seconds. I opened and closed the door again and voila – everything was back to normal. A day or two later … same thing happens again. I was thinking to tape that door but I know it's only a temporary fix. What's causing all this? Why is that door opening ever slightly after a day or two? What can I do to fix this permanently?
What could be causing the furnace burners to fire up, then shut off due to partially open door
furnacerepair
Best Answer
There's likely a switch that senses when the door is ajar attached somewhere near the edge of the door opening. Sometimes the switch presses against a little feltlike pad that can become depressed over time. That'll release the switch and tell the furnace that the door is open when it's not. Replacing or thickening that pad may well solve your problem. Oh yes, while you're in there: cleaning the pilot, sensor, and blowing out the burner box is always a good idea.