I have been having an intermittent Rheem air conditioner/
heater problem. The blower won't shut off unless I cut
the main power. The furnace shuts off fine. Switching
off the fan or anything on the thermostat won't shut it
off. The technician says that they won't repair it unless
they find it dead. By the time the technician arrives the
AC is working again because it usually fails at around
1-4AM then resumes working again at 5AM.
I am now deciding to replace the parts myself but
need some help. I'm not certain but I think the
symptoms point to the blower relay D7 or the fan
cycle control switch F7 on this schematic diagram
Where is the fan cycle control switch is located in the
Rheem heater - is it inside the furnace?
Don't know the Rheem brand but usually it's the fan/limit module either
being set too low for the shut-off temp or the module is broken.
Considering that it's cold this time of the year the chance that it's
broken is high. This link seem sto explain it pretty well:
Do you mean the fan that circulates the air through the house,
assuming it is a forced hot-air, cold air furnace?
There is a switch that controls when the blower is on, in the heating
cycle, that keeps the blower running until the plenum temperature goes
below a certain level so that as much heat as ppossible is
extractred. If that switch contact is physically sticking, the blower
will run continuously. But you indicate turning the main power switch
off and then back on fixes the problem, so unless there is mechanical
vibration when you cycle the power, there is something else going on.
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