arby808
Mar 30, 2019, 10:50 AM
Hi I have a carrier weather maker sxI furnace that has a code 21 and locks the furnace. When the house gets cold I check the thermostat and see it is calling for heat the stat is new. I go to the furnace and shut the power off and the furnace will start running, some times it will work for a hour and sometimes it will work for days or even weeks what would cause this