A manual fan on switch could be set at the thermostat or at the limit switch in the air handler furnace itself or wires could be shorted together in the thermostat wiring or there could be a bad fan controller itself.
Wall mounted gas heater troubleshooting.
On 2017 10 10 by mod wall mounted gas heater fan runs even though the thermostat is off.
It should be parallel to the pipe.
Periodically inspect all burner flame holes with the fireplace running.
Pilot light will stay lit.
If you re wondering why your heater is blowing out cool air the first thing you should do is check your thermostat and make sure it s set to the correct temperature.
If there is or your heater runs on natural gas check the handle on the gas line.
You may have a bad thermocouple.
Either remove blockage or replace burner.
All slotted burner flame holes should be open with yellow flame present.
But when you turn the pilot to on the unit burner and pilot go out after about two minutes.
Try kicking it up a notch to see if there s a noticeable difference.
If so turn off fireplace and let cool.
Heater is blowing cold air.
Off grid wall mounted empire direct vent heater.