My furnace was fixed on Monday, just a few days after stopping working. I called Echols because of a sticker on the furnace and the fact that they work on Carrier furnaces. They came about an hour later. It took the guy very little time to figure it out. I guess it was just some blockage in a tube going to the pressure switch, making it not work properly. He just blew it out. We had checked that, but apparently not well enough. He did some more diagnostics, but that was the only problem. $116 and my furnace was back in operation.
I had seen that it was throwing code 31, which implies that the pressure switch isn’t working correctly on Carrier furnaces. I investigated myself a bit based on some things I saw online. I cleaned out a condensate trap, which was filled with some algae looking gunk. I also checked the tubes going to it, but they seemed clear. My dad later came to help looking at it. We figured out where the pressure switch was, one tube away from the condensate trap, and checked out some more tubes as well as the vent pipes and other things. We couldn’t figure it out. I looked into and he blew through the very tube that was the problem, but I guess not well enough.
Once the guy got it running again, it went to work for over an hour heating my 66°F house back up to temperature. I had managed alright with the electric heaters, but it was definitely getting chilly in there and took some work to move the heaters based on which room I was going to be in. I definitely appreciate having a working furnace. Hopefully it keeps working for a long time.