The compressor on the roof (also Lennox, seemingly wired in correctly) will run as expected, and proceed to ice up the lines, and the indoor blower relay will make a nice click, but the motor will not start. it does not get hot, and it does not hum, and the squirrrel cage turns freely.
Investigating with my VO meter finds that the motor is getting voltage. It seemed at first that it was getting voltage on two different speed wires at the same time, but in fact it is only getting it on the black wire. Apparently, the black and red wires are shorted together inside the motor
that is, when I insert the Common probe into the wirenut for the Common that goes back into the wall, and touch the hot probe to the relay terminal that's supposed to energize the blower when cooling, i read ~110 volts
and when i touch it to the terminal that's supposed to be energized when heating, it also reads ~110 volts. But the terminal isn't actually energized (as I verified by disconnecting the blower from it) Nor is the wire from the fan control box that keeps it running until the heat exchanger cools. no, just the wire that supposedly feeds voltage into the blower motor
the only manual i've found for it is this one:
I'm hoping someone can tell me whether this means the motor has failed, or if maybe it's just one of the speed wires?
Oh, I forgot to mention. The fan doesn't turn on when in heat mode either. though this might not mean anything, since that's the wire that had voltage when i thought it shouldn't
Edited by dna48, 17 May 2012 - 04:17 PM.