2HP AC Single Phase Motor very weak at start or hums 4

[Smyers75]

I have an A.O. Smith 2HP, 220Single-Phase pool pump motor that started giving me trouble.

It has been working for the past year or so, but just started having starting problems.

When I turn it on sometimes it starts, most of the time it just hums.

If I give the shaft end a spin, it will always start but I can always hold on to the shaft with two fingers and it will never start.


I did a search here and saw the answers about the cap possibly being bad, but I did the VOM test at 10K and it seems to pass.

After discharging it, it starts out at zero ohms then takes about 10 seconds to swing across the dial.

I read about looking at the centrifugal switch, but I think this one doesn't have one...or is it I just don't know where to look?

I attached a link to the manual for this motor.


Should I try replacing the cap, even though it seems to pass the test?

Shouldn't this motor have way more starting torque than two fingers of a weak, computer programmers hand?

 

[lukin1977]

I once had the same problem with a motor.
It spinned but I could stop the shaft with my hand

The problem was the squirrel cage. It was damaged
I had to replace the whole motor

 

[zlatkodo]

This may occur also because of low power supply voltage or too long connecting cable.
Can you measure the voltage on the motor when it tries to start (without your help)?
Also you can try to add second cap (you already have it). Connect it in parallel with the first cap, through the push button (or just manually for testing ), but only temporarily, during a start.
Note: discharge cap before working on it!
Zlatkodo