HVAC blower trouble

[tom slick]

A start capacitor "splits" the phase by 90 degrees to allow a second set of windings in the motor to "push" the rotor and start rotation. There is a centrifugal switch in the motor that closes when the motor is stopped and open when the motor is at operating speed. That switch controls the start circuit.

Without the start circuit the rotor doesn't have a force to make it start spinning. It just sits and hums because the forces are equal in both directions.

If you want to read more on the electronics side read about how capacitors and inductors interact with AC.

IF your local HVAC supplier (i.e. Ferguson) will sell to you then you can buy it there. Otherwise you may have an electric motor rebuilding/rewinding shop locally.

A start cap might cost $10.

 

[nazareth]

ge actually makes good motors. fasco too. i wouldnt go searching for motor there are 2 type bearing sleeve and ball. ball tend to me a little noisier but last longer and stand up to heat better. most ge motors are ball bearing..i would stick with what you have i doubt your run cap is a 5mfd probably a 7.5 mfd or 10 mfd..reguardless get a 440vac

 

[nazareth]

btw its not a start cap its a run cap. there is actually a differnce

 

[brianl703]

Originally Posted By: BearZDefect

At this point, my next question is, what kind of store do I call for a replacement capacitor?


An electrical supply may have them. Any place that rebuilds electric motors definitely would.

 

[BearZDefect]

Update:

8am this morning I called a local HVAC shop I am familiar with, their tech arrived by 2pm. He checked the capacitor and said it was weak at 6 microfarads, replaced it with a new one measuring 7 microfarads. I didn't think that was a big difference.

It does start with the new capacitor, but it is still a lazy (slow) start. He suggested replacing the motor, given how noisy it is, and reported that it was drawing less current than the spec. Said these GE motors have their own mounting scheme so cannot substitute another brand. They didn't have any in stock, would have to order one.

I haven't seen the bill for today's work, but the estimate for replacing the motor was $250.

Thanks to everyone for all the help. I learned a lot!

 

[BearZDefect]

Conclusion, I hope:

8am this morning the blower motor gave up completely. I could not get it to start moving again.

Called the pros again, they made it here around 3pm to replace the motor. Meanwhile the house got rather chilly.

The new motor is much quieter.

They said the motor was more expensive than they had anticipated. The bill promises to be steep.

 

[Quest]

Sorry to hear that (the motor finally kicked the bucket).

Good news is, you now have a new motor to run your heatpump so no more worries. Bad news is, it might cost you a few hundred mullahs more ....

Oh well, it's not the capacitor to blame for (per my hunch).

Take care and stay warm.

Q.