This is a wierd issue, but I will do my best to explain it. Any advise
is greatly appreciated.
I have a newer Trane A/C installed last summer. The A/C works great.
If the fan is on auto and I set the thermostat at 75, when the temp
reaches 76 it turns on, when it gets down to 75 the fan and a/c turns
off, just like its supposed to.
The issue is with the heater. If I turn the fan to auto, it never
comes on, but if I turn the fan to "on", the heater works great. The
issue is, I have to leave the fan to on, which means it will run until
I manually turn the fan off, even if the heater kicks off. For
example, if it is 74 in the house and I turn the thermostat to 75 and
switch the fan to on, the heater kicks on and pours out heat until it
hits 75, but the fan keeps blowing after the heater turns off. If the
temp drops a degree the air the fan is blowing becomes hot again.
Everything seems to do its part, but the auto fan on the heater side,
even though it works fine on the a/c side. I figured it was a faulty
thermostat, but I've tried four different ones and they all do the same
More info on the unit, it has 4 wires to the thermostat, White, Yellow,
Red, and Brown (Ground). There just isn't much to it. The heater is
Does this make since, any ideas?