I have a 15 year old Trane gas furnace. The thermostat is a mechanical
White-Rogers. When I initially turned on my furnace for the first time
about one month ago initially the heat would not come on set to AUTO.
After having the heat run a while on ON, I switched to AUTO and all
worked fine for the week of cold nights here in NC. Temps rose to the
mid 70's, so I cut the heat to OFF. Now temps have dropped to again and
last night I turned my heat on and again AUTO would not work. I
switched to it to ON and it worked just fine. Switched to AUTO after
house warmed up. THis morning it was 55*F in my house. Turned furnace
to ON to and house warmed up, however, warm air stopped blowing, just
cool fan air. Today after work, I checked and the pilot light was out.
I lit the pilot light and turned the furnace on, again works just fine
on ON, but will not work on AUTO.
Does this sound like a thermostat issue or something else at the control
box on the furnace.?? I was going to replace the old themostat with
digital themostat to see if that fixes my problem. I also have a HVAC
technician/repairman coming next week to check out the problem in case
replacing the thermostat does not solve the problem.