We've got a whole-house fan - and for about the last year, the thing's been having speed problems. I thought it was the controller - the speed control just wasn't working and the fan was running slowly. Well, with spring being here and the temperatures FINALLY warming up - (It's May, and we haven't had to turn on the air conditioning yet...) I got a replacement controller and installed it...
And the motor ran fine for about a minute... then the speed controller wouldn't affect things at all and it slowed to it's usual speed.
The motor was made in 1979. I suppose it wouldn't be too surprising to find the motor has failed. I found a replacement on-line (and for a lot less than I was expecting to pay) and was about to buy it (and the capacitor needed to start and run it...) when I noticed a FAQ section.
Well, what the heck. Might as well check out the return policy... but it was technical questions instead - including about capacitors...
And there it was - an answer to what might be wrong with the motor.
Question: A motor with a shorted capacitor can still start and run, but will operate as if seriously overloaded True/False?Haven't ordered the motor - but I ordered a replacement 5 MFD capacitor. We'll see if that takes care of the problem...Answer: True
(Well, THAT pretty much describes what's going on...)
Question: Capacitors for PSC (Permanent Split Capacitor) motors are only used for starting the motor True/False?
Answer: False
(So they're needed to run the motor as well...)
Question: Run capacitors are oval shaped with single MFD (Microfared) ratings True/False?
Answer: True
(The one on the motor is oval-shaped. Didn't see any MFD rating on it...)
Question: It is possible for a Permanent Split Capacitor (PSC) motor to operate even if the capacitor is shorted True/False?
Answer: True
(But apparently it'll run like it's badly loaded down....)
Question: Capacitor life is about how many hours?
Answer: 60,000 hours.
(Let's see - 24x365x30 give well north of 200,000 hours. Not all that time was running the fan, of course - but we've run it pretty constantly in the spring and fall... and I'll make a leap of faith here and figure the thing's gone bad.)
J.