weird pool pump motor failure symptoms

Diver

Well-known member
May 5, 2011
477
South of Boston
So couple of days back I found my pump dead. I have superpump with “A.O. Smith STS1072RV1 0.75HP 230V Dual-Speed 56J Frame C-Face Motor”. See attached.

I checked the large capacitor in the hump of the motor and it was dead. I ordered a new one and installed it today. Turned the switch on and the motor started humming and making little crackling noises. I turned it off and switched to low speed and tried it again. To my surprise it actually started. I let it run for a bit and then turned it off, switched to hi speed and turned it on again and it was running!

I stopped it again, waited a little and try to run it on high speed again and nothing but humming. Tried the low/high speed trick and it didn’t run. Started it on low again and switched it to high without powering it off first. It ran.

So I’m thinking maybe both running and starting capacitors were dead, I replaced the running, but starting one is still dead. It’s easier to start on low speed and once the shaft is spinning, I can flip to high speed and it would keep going.

Apparently this motor is permanent split capacitor motor and they only have one capacitor. So my theory doesn’t seem to hold water. What is also strange is that intheswim blog page that explains the different types of motors, has a motor that is mirror copy of mine listed as “capacitor start – capacitor run” (see attached). So I’m confused as I have a single capacitor or double capacitor motor now.

Anyone can shed some light on this weird problem?
Thanks!
 

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JamesW

TFP Expert
Mar 2, 2011
23,314
Do you have a picture of the motor label?

If the motor “type” on the label is CXCP, it’s a capacitor start, capacitor run motor.
 

JamesW

TFP Expert
Mar 2, 2011
23,314
I remember when you put the motor in.


I believe the high speed is PSC (Permanent Split capacitor) and low speed is capacitor start induction run.
 

Diver

Well-known member
May 5, 2011
477
South of Boston
James, I'm an idiot! Somehow after testing the new and old capacitors together, I managed to grab the old dead one and install it back to the motor. And then managed to get the motor somewhat working while starting it on low speed.

I went back and fixed it better this time and it runs and sounds like new! So the mystery is solved.

But i still wonder if there is another capacitor under the cap. But I will find out next time if/when it comes.

Thank you for your help! As always your knowledge is appreciated!
 
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