I have a Trane heat pump.Inside unit is about 13 years old, the
outside unit is about 8 years old. I think it is a 3 ton unit.
Original weathertron thermostat.
During a recent cold snap (outside temp about 15), we noticed the
house temp wouldn't get above 65 F. The blue aux heat light was on but
I don't think the heater strips ever energized. To test, I measured
the air temp at a vent before and after the blue light came on. No
difference. Then I tried switching to emergency heat. This cut out the
compressor (as expected) and the vent temperature started to drop. So,
I think the the emergency heat is also not working.
I checked all the breakers. What do the emergency heat strips and the
aux heat strips have in common? I'm thinking that they share a common
ground that may be bad? Any other ideas?
There will likely be another set of breakers on the inside of the air
handler, suggest should check them also.
Uses the same heating elements--just that when the thermostat is set to emg
then the heat pump compressor will be locked out altoghether, when used as
auxillary then they only fire when the heat pump can't keep up with demand
and so the thermostat calls them up as second stage supplemental heat ( and
if wired up properly, they will also fire whenever the outside unit goes
into defrost mode )
Suggest trace the white wire that runs between the thermost and air handler,
oftentimes folks will disable the heat strips by disconnecting low voltage
control to it--thus forcing heat pump operation only--which in many cases
can save considerably on the electric bill at least during mild weather...
Variations of the above do exist--for instance, could be that you have an
outdoors lockout thermostat and it has been set to disable heat strip
operation at temps above 15 deg....but, beings as no one can see it all from
here then really the best thing would probably be for you to call in a
Actually, looking over your post again it appears you very likely have
something fairly serious has gone wrong--beings as the strips apparently did
operate at least for some period of time.
Definately suggest it's time to call in a tech.
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