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Dan Lanciani

In article , (Jud McCranie) writes:

| I'm having a strange problem with the A/C (a heat pump). One night
| near the end of last summer we had some lightning. The next day our
| upstairs A/C started blowing hot air so I called the A/C repair. They
| topped off the coolant, replaced the capacitor. They also said that
| the thermostat was calling for the heat strips, so the thermostat was
| replaced. The A/C was working. A day or two later the A/C was not
| blowing cool air. I determined that the compressor was running but
| the fan compressor was not turning. But the problem was intermittent.
| Anyhow they came back out and replaced the fan motor. It worked for
| about two weeks, but it was always noisier than the old one they took
| out. Then it quit working some of the time, but the problem was again
| intermittent. I had a hard time getting the fan to quit turning when
| they were out here, but finally it happened. They said that the motor
| they had put in was defective, and they put in another one. This
| motor was quieter than the one they replaced. This was near the end
| of summer, so soon we didn't need cooling anymore. They made a total
| of five trips.
|
| Skip to about two weeks ago, once again cooling is needed. It was
| working, but I heard it make a loud noise, and the compressor fan
| stopped turning again.

It seems unlikely that you had three bad fan motors. Given that it is
a heat pump, the obvious guess is that a damaged defrost controller is
erroneously entering defrost mode. On my heat pump defrost mode turns
off the outside fan and turns on the secondary heat (heat strips in
your case). You might want to check whether your heat pump is (was?)
wired to be able to energize the heat strips during a defrost cycle.

I have one of the auxiliary indicator LEDs on my thermostat connected to
the secondary heat line. The thermostat already has an LED to indicate
that it is calling for secondary heat and this LED is conveniently _not_
turned on when something else (in this case the heat pump's defrost control)
drives the secondary heat line. The combination of the two LEDs makes it
easy to notice when something funny is going on.

Dan Lanciani
ddl@danlan.*com