My gas furnace won't turn on when it's set to heat. My girlfriend and I both noticed that it was a little cold today. I went to flip the heat up a notch after dinner, and that's when I noticed that it's 63 in the house when the thermostat is set to 68. I've been doing some troubleshooting/watching YouTube videos and googling. I stumbled upon this board, so I thought I'd ask to see if some kind soul can help us out. Here's what I did so far:
- I flipped the breaker switches in the electrical panel for both the A/C and the furnace
- I switched the batteries to the thermostat (it powers without them, but i figured worth a shot).
- I flipped the fan from "Auto" to "On" on the thermostat. Interestingly, the fans in the house will kick on if I have the theromstat set to "Cool", but not if it's set to "Heat".
- I took the cover off the furnace (where I change the furnace filter). I am noticing the panel has a light that is blinking green 4 times when I hold down the sensor that tells the furnace if the cover is on or not. I'm not sure if the 4 times means something or not, but worth a shot.
That's as far as I've gotten. Any ideas?
We're trying to avoid a cold night…
Photo of the label inside:
Best Answer
Sounds like the furnace may have failed the first diagnostic test for the draft inducer. If the system doesn't detect a positive pressure to the pressure switch after the inducer motor starts, it won't let the burner igniter operate and throws a 4 flash code. Sometimes the tech just needs to remove the vacuum hose from it and clean out any debris that may be plugging up the hole or the hose and put the hose back on and it will run.