by Lou
(Foster RI)
30 gal. Craftsman 919.167310. No air in tank.
Tried different amp sockets of 20 and 30 amp. Does same thing.
Tried replacing capacitor of the same type (30 mf- 370v). No joy. Compressor does exact same thing with NO capacitor wired in. Turns fine by hand.
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Initial start up blows breaker
Sounds like the centrifugal switch is not closing properly when the motor is stopped.
Which happens to explain no difference when there is no capacitor…
Hope that’s it, as otherwise your start winding may be kaput.
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Centrifugal switch
I took off the back plate to get at the points. They were together when stopped. I filed them clean and restarted the motor. They pulsed when I attempted to start the motor but stayed together. Points did not appear to “open”.
It seems Sears does not sell the centrifugal switch separate nor does it carry this motor any longer.
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Initial start up blows breaker
Bummer.
If we’re certain it only has one capacitor, then it seems the motor is bad – for whatever reason.
If you can get it to a motor shop to bench test it, that would be good, and they’ll probably have a similar motor in stock if you need one.
If that’s not practical, I’m afraid it’s time to go shopping for either a motor or new compressor.
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Centrifugal switch for compressor motor
All may not be lost. It appears as though there are some commonalities among centrifugal switches.
If you Google “buy centrifugal switch for compressor motor” as I just did, you will find a) lots of info b) sources to obtain them.
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Why not the starter cap?
There is a 136-163 mfd starter cap within the back plate made by Mallory. 220 vac. How close do I need to come to this output for a replacement. Can I go larger if the unit fits within the motor?
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New capacitor
The page on this site that talks about sourcing capacitors says “if the new capacitor has the same voltage range, the same microfarad range, and you can attach it to the existing mounting of the motor capacitor on your compressor, you can use it. Even if it’s a different shape, a different color, longer or shorter or bigger around, as long as the voltage and microfarad ratings are the same, it is a suitable capacitor for your compressor motor.”
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Capacitors
OK, I had thought this might be a one cap thing. Since it has two, that means you replaced the run cap, given the values we now know.
136-163 mfd 220V caps are readily available. If you have one on hand that’s larger, with at least a 220v rating, that may well be ok since it’s only in the circuit for a brief time during start-up.
What cap (mfd and v) were you thinking of trying?
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Found capacitor
I searched the net and found a company that sells this exact capacitor for the A.O. Smith motor on this compressor.
Will let you know if this works.
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