Noob with Pump problem

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pielut

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Oct 1, 2013
8
Glendale, Az
Hi All, just purchased my first forclosure. Great house with a great play pool. Everything worked great during inspection and now that I own the place, I have a pump issue. The AO Smith motor will turn on and pump water for about 5 seconds, then it tripps the 15amp breaker. I replaced the breaker in hopes of a failed unit. No go. Still tripps. Not sure that it's a capacitor since it starts. Maybe a short in the wiring? Looks like a ST1202. Should I have the motor checked by a shop? Buy a new motor? Thanks for the help.

 
That your pump starts up fine and then kicks suggests that you are overloading the motor. Debris stuck in the impeller is usually a common cause but it could be other things as well..

When the motor kicks, can you see what your psi is at the time it pops the breaker?
 
Why do you need such a large pump? Is there water features or spa that's not in your sig?

That pump draws 12 amps normally, so you're already close to what a 15 amp breaker is designed for.

What is the filter pressure running when it's running?
Have you removed or changed any eyeballs?
Have you changed anything to get more flow?
 
Right now I have a 2 pole 20 amp breaker and 12 gauge wire, still tripping 20 amp breaker. Electrical panel is on opposite side of pool equipement, so long run. When the pump turns on all is well until pressure starts to build. I reach 3-4 psi and the motor dies. I do have a water fountain. No changes to eyeballs or pressure that I'm aware of.
 

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Assuming there is no blockage and the impeller spins freely, you might have a bad run capacitor. That is the one that is under the hump on the top of the motor. A bad run capacitor can overload one of the motor windings and make it run hot which will ultimately trip the breaker.

A run capacitor is one of the easier things to change on this motor and only involves removing 2 screws and the top cover (breaker off!!!). You'll see 2 wires that clip into the capacitor. Any buldging or discoloration of the capacitor would be a clue to a possible bad unit. You would need to read the Uf or MMF reading and voltage on the label and purchase an identical unit. Prices can vary widely and from $35-$40 at a pool store to about $13-$15 at Granger or possibly online. Usually this capacitor is a 30 MMF, 370 volt AO Smith # 628318-308, but you need to confirm that and it doesn't have to be the expensive AO Smith OEM capacitor. Some appliance parts stores carry these too, but just make sure the canister size is about the same as yours so it will fit under the hump cover (and not short out).

Of course there are no guarantees it is the capacitor, but for $15, it may be worth a gamble. At least that is what I would do.

EDIT, I found this You Tube Video with more info: http://www.youtube.com/watch?v=k-cVgpz7GYQ
 
pielut said:
So I replaced capacitor with a new one and same problem. Motor runs less than
10 seconds and trips breaker. Before it dies, pressure increases slowly to 3-4 psi, water
starts to move in the pump and then nothing. Any more ideas?
Click to expand...
The only other thing I can think of, short of replacing the motor, is a bad start switch on the back of the motor. There is a little white plastic square piece about 1/8" X 1/8" that sometimes breaks off the start switch. This piece rides on the end of the centrifigal switch (dead center to the motor shaft on the back). Once your motor starts, the switch releases that plastic piece and that opens the start switch which cuts the start capacitor and the start winding out of the circuit. I had this happen on one of my motors. If the start switch can't pop open, the motor rapidly over heats and trips the overload or the breaker to protect the motor. If I get time later, I'll show you a picture.
 
Adding to my above post.... I found a picture of the back of the motor in a post here on the TFP forum. I'm going to link the picture with the hopes that the OP and mods won't be upset with me (I can always delete). The start switch in this picture may look slightly different than yours, but they wotk the same way. Mounted on the shaft is a centrifigal switch (see the springs). As the motor gains speed from start (in less than 1-2 seconds), that switch opens and removes the starting capacitor (black one in the back) and the start winding from the circuit in normal operation. In your case, it appears that the start switch is not opening as mentioned in my above post. Inspect the switch for anything unusual.

L1150622_zpsd089c9e9.jpg

I probably should mention that this motor is probably getting some age on it. Assuming the windings are good and the problem is just the start switch, you could probably fix it, but keep in mind that the bearings, or even the starting capacitor could go out sometime in the near furure.

Here is a picture of the old style start switch with the plastic tip (top of switch in this picture) that sometimes breaks off.

my9w5tErvWTMk1LPUtUDN3A.jpg


EDIT: I found a great You Tube video that shows the switch in action. Its much better than I can explain:

http://www.youtube.com/watch?v=LDeCljJDMdg

Another Edit (sorry if this is information overload :) ) Check out this E-Bay listing. I have bought from these guys before with no problems:

http://www.ebay.com/itm/A-O-Smith-motor ... 380wt_1170
 
Thanks for the info hoosierrun. I tested the motor separate from the pump and it still shuts off after a few seconds.
I read that pumpwarehouse.com has good prices on new motors. I've tried for two days to reach them. Are they still in business? Can you guys recommend another source for motors. Thanks a bunch.
 
pielut said:
So I replaced capacitor with a new one and same problem. Motor runs less than
10 seconds and trips breaker. Before it dies, pressure increases slowly to 3-4 psi, water
starts to move in the pump and then nothing. Any more ideas?
Click to expand...
Did you replace the run capacitor or the start capacitor?

If you do replace the motor, I would recommend getting a 2-speed. The a.o. smith B2979 or B979 would be a good choice. Here is a well priced one: http://www.poolsupplyworld.com/Cent...4-HP-34501725-Pool-Pump-Motor-230V/B2979.htm#
 

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