My Wall mounted thermostat seems not to work when put on auto for heat, but when switched to just ON, it starts running continuously. Is it my thermostat gone bad? if it is, and how can I change it. Would appreciate any good answer.

benjee.

Do you mean, when set to demand heat, the furnace blower does not run unless you set the t-stat fan selector to "ON"? If so, the problem may lie in the indoor blower control, not the thermostat. Specify brand/model # of indoor unit, and system type (gas or electric?).

Yes, it only run when set to the ON position and not run when set to auto. I am currently in Memphis, and the system is in GA. I will return to GA Monday evening and I will furnish you the complete detail of the system. I know it is a gas system.

If it is indeed a gas furnace, the problem you describe is related to the fan control in the furnace or the blower motor wiring, not the thermostat. While you are there, try to take a peek at the furnace control area for anything that looks suspicious.

Good morning KC,

I had just checked the whole unit, one thing I noticed was that, first of all,

The system make is Lennox 80UHG SERIES. When I turned on the thermostat, and turn the switch to heat, and fan control to auto, there is no action. But when I switched the fan control to just ON position, the system runs and blows cold air, but when I went upstairs in the attic to check the whole unit, I did not see anything unusual, except that the light in the furnace is not light, by that I mean that the gas was not gushing out and fire burning inside the unit itself but I heard the blower working.

When I checked the thermostat it appears that the thermostat may have been damaged by my wife friend. I do not understand the whole thing at all for the thermostat not to run in auto and then run in the on position, is quite puzzling and when it does run in the on position its just blowing cold air and no heat. I even tried the switch close to the unit upstairs and the switch works fine, because when I turned of and on I heard a click and the humming noise in the unit in the on position, that kind of make me to conclude that the system might be OK. I will leave here my personal cell phone number, if you want you can reach me at my cell. I need help here. Thanks.

Ben.

678-778-2049.