I know this has probably been discussed a lot. I've searched and cannot
find anything that specifically addresses my problem.
I recently bought a home in Western Kentucky. The house has a heat pump.
When the temperature reaches low 40's and below, the alt button lights up.
From what I understand, this is normal and indicates the heat strip is
coming on in conjunction with the heat pump in order to keep up with the
heating needs. Yesterday, the registers started blowing out nothing but
cold air. Even with the thermostat turned up to high 80s, the temperature
in the house is 67 degrees maximum. I turned it to emergency heat, which I
believe means that the heat strip is being used without the assistance of
the heat pump. Still no warm air. I have called a repair center and they
will be here sometime next week. We have a gas log fireplace in the
meantime which keeps the house fairly warm, so at least I am not freezing in
Since the house is only 4 years old, I wonder what could have caused this.
The previous owners had the filthiest filter in the cold air return that I
have ever seen. I doubt very seriously if it had been changed in the four
years that they owned the house. I change ours every month. Could this
have led to the problem? Any thoughts are very much appreciated.
Generally the power to a heat pump comes from several sources, a
breaker for the fan, a twin breaker for the outside unit and one or
more twin (220 volt) breakers for the strip heaters. You may want to
check to see that all the circuit breakers are on. There may also be
one outside by the heat pump unit instead of a disconnect. Remember
that you flip the breaker first to off then back on as the tripped
position is in the middle and sometimes hard to see. Also a modern
thermostat does not cause more heat to be produced at a higher setting
unless its a multi stage model. Any setting high enough to get the
heat operating gets full heat production, if the unit is working. Good
luck, after service you may find that the unit was low on refrigerant
and actually works a bit better.
If no heat is produced in the E-Heat Setting, you may have a thermostat
problem, or the strip heat itself has failed.
There is probably only one breaker to the air handler, and even though the
fan is running, one leg of the 220 may not be present.
Quick check of the outputs of the breaker would show that (or feed terminals
in the air handler).
In standard heat mode, have you verified that the compressor is running?
You can't miss it when it is on.
As far as low temps when everything is running, you may need to have the
charge checked. It should make fairly
warm air when the outdoor is at 40 or so. A service tech can check
temperature at a register and will know about what it should be for given
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