Quote:
Originally Posted by Rick Parker
I've got an intermitant problem with my home furnace that I'm attempting to fix. The fan motor is attached directly to the squirrel cage without any belts or pulleys. It is a Rheem Highboy unit, '79 vintage combination heater/AC unit. When the burner lights, the heat/cool fan relay clicks signaling the motor to start. The capacitor start motor just "hums" without begining to spin. I can manually give the squirrel cage a nudge and it starts spinning without any unusual noises. Question: assuming the motor itself is OK, do capacitors fail or loose their ability to store energy to provide the bump? In removing it from the unit, what is the correct way to discharge it.
Thanks
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I think you've gotten good advice. One point I question is that if this an intermittent problem, it doesn't sound like it is the capacitor to me. I've always thought that once a cap fails, it's done permanently.
On the other hand, I think some motors have a centrifugal switch that always starts the motor with either an out-of-phase separate winding or temporary insertion of a capacitor in parallel(series?) with the main winding which causes the main winding to start with a phase shift that gives it intended direction.
If you hear a click from the motor after the hand-started motor comes up to speed, that may indicate that a centrifugal switch has kicked off. This could mean that the intermittent problem is due to bad internal switch contacts. I think that contacts are more likely to be intermittent than a capacitor. Just a thought.
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