Pump motor hums, impeller spinning, phase winding or switch?

ZenoParadox

New member
Jul 29, 2020
4
New Jersey
Hi Everyone. I have a Century AO Smith (I think 1 HP, it's a little unclear) motor. When I went to start it, it would just hum and pop the circuit breaker. I tried to manually turn it with a screw driver, but couldn't get it to start. I resorted to using a power drill, which I ran for a few minutes, and I had the motor shaft spinning freely. I ran it for a few hours, and everything was fine. The next day, it was completely frozen again. Used the drill, got it going. The next day, it started up, ran for about 2 hours (probably the best I've ever heard it run), and out of nowhere it shut off. Here's where I am a little lost. The impeller and shaft still spin very freely, but when I turn the power on, it completely binds up. The second power goes off, it spins freely by hand. The motor doesn't have capacitors. I'm trying to figure out why it binds when the power is applied. Could the switch somehow be tripped, or bad phase windings, or something completely different? I have a new motor hooked up and running the pool, and was only going to keep this as an backup (though I don't plan on the current one breaking anytime soon). I'm really curious why this isn't working, because it seemed like it would stay running for a long time after the initial corrosion was all broken free. Thanks in advance!
 

JamesW

TFP Expert
Mar 2, 2011
20,740
The Type is SP, which is Split Phase.

It doesn't have a capacitor. It does have a start switch.

Check the start switch contacts.
 

JamesW

TFP Expert
Mar 2, 2011
20,740
Here's a test you can do:

1) Turn off the power.
2) Disconnect the power wires from the motor.
3) Disconnect the wires from the centrifugal switch.
4) Label the centrifugal switch wires S1 and S2.
5) Measure the resistance between
L1 and S1
L1 and L2
L1 and S2
L2 and S2
L2 and S1
 

ZenoParadox

New member
Jul 29, 2020
4
New Jersey
I just took the whole thing apart. The bearing in the back is torn to shreds, and the fan at the front by the impeller is broken in half. I haven't been able to properly test the resistance yet (I'm not completely sure which terminals are which, and I'm not good with specific part names but I don't see wires to the switch, the part that has springs on it...all the wires are on the "control board" and don't go to the switch but somewhere in the windings), but seeing the broken parts, I'm not sure it's really worth fixing as a backup. I'm not really having luck finding parts for it, and I'm not convinced it didn't just burn out. Thank you for the ideas so far. If I can determine the resistance, should that tell me if it burned out?
 

JamesW

TFP Expert
Mar 2, 2011
20,740
I think that the motor is from 2002. At 18 years old, it's probably time for a new pump.

If you can test the resistance, that should tell you if the windings burned out.

Do you have a picture of the wiring compartment?
 

ZenoParadox

New member
Jul 29, 2020
4
New Jersey
I think that the motor is from 2002. At 18 years old, it's probably time for a new pump.

If you can test the resistance, that should tell you if the windings burned out.

Do you have a picture of the wiring compartment?
I knew the motor was old, I didn't realize that old! Is there an online spot that gives that sort of information? `I'm going to look into testing the resistance more (motor diagnostics is new for me.. I'm familiar with engine repairs, but this is a first for me with motors). I've attached a picture of the top of the wiring, do you need one showing where the wires go?20200730_195116 (1).jpg