Can anyone help? My carrier 58MCAD80-12 furnace is not providing any heat. I’d had a problem with my humidifier, and had just repaired it. I had been running the furnace at 80 deg for a few minutes to make sure the humidifier was working properly. When I wanted to adjust the temp back to 70 deg, I found that the LED display on the thermostat was blank – just as if the power switch of the furnace was off (but this was while the furnace was still running) I also noticed then that the furnace was blowing cold air.
What could I have done to cause this problem? Or is it possible that it’s a totally unrelated problem that just happened to occur while I was working on it?
Thinking that perhaps something may have gone wrong with the thermostat, I replaced my existing thermostat. The problem persisted – still no heat. The flame does not light up in the burner.
I then did what I should have done first, and went through the troubleshooting steps in the manual. I am getting a code 34 LED code (Limit Circuit Fault) which continues for a while, and then changes to a 13 LED code (Limit circuit Lockout). Under LED code 13, the manual says the “Control will reset after three hours”. Nothing changed even after three hours.
As you can probably tell, I’m not very savvy with HVAC equipment, but wouldn’t want to call in a repairman unless I absolutely had to. Can anyone help?