Pentair 2 Speed Pump Won't Start on Low Speed (Only)

[Beach_Bum]

Hello, first post here.

I'm having a problem with a 2 year old Pentair Whisperflo two speed pump. The pump will no longer start on the low speed setting like it used to, it now only hums. I can change it to high speed while it's humming, and it will then turn on. When I switch it back to low speed after getting it running, it will continue to run as long as I let it. I've searched other threads on the forum, and have tried replacing what I believe to be the start capacitor (under the hump on top of the pump) with the exact same model that previously worked, but that did not correct the problem.

The pump is controlled by an Intermatic electronic timer.

Thanks for your help.

 

[mas985]

Welcome to the forum!

My guess is that there is corrosion on the centrifugal switch contacts in the back of the motor. Try cleaning the contacts.

 

[Beach_Bum]

Welcome to the forum!

My guess is that there is corrosion on the centrifugal switch contacts in the back of the motor. Try cleaning the contacts.

Thank you. I will give that a try and report back this weekend.

 

[Beach_Bum]

Welcome to the forum!

My guess is that there is corrosion on the centrifugal switch contacts in the back of the motor. Try cleaning the contacts.

So I finally got around to checking the motor this week, but didn't have much luck locating the switch contacts. I've attached some pics of what I found when taking the back off of the motor.

 

[mas985]

The switch rides on top of the motor shaft so inside the back end of the motor. You might be able to see it through the top opening in the first picture. Also, you may have to remove the other three screws on the outer edge of the motor to get to it.

 

[Beach_Bum]

The switch rides on top of the motor shaft so inside the back end of the motor. You might be able to see it through the top opening in the first picture. Also, you may have to remove the other three screws on the outer edge of the motor to get to it.

I'll give that a try this weekend. Thank you for your help!

 

[Beach_Bum]

The switch rides on top of the motor shaft so inside the back end of the motor. You might be able to see it through the top opening in the first picture. Also, you may have to remove the other three screws on the outer edge of the motor to get to it.

So I finally got around to opening up the back of the pump today and wanted to post my findings in case this happens to anyone else.

The problem was a broken spring on the top side of the switch (there are 2 springs total, one top, one bottom). Luckily the spring landed by my feet when I pulled the back of the motor off or I probably would have never diagnosed the problem. There are 2 "hooks" on each end of the spring and that is what broke on one side. I did not have an extra spring handy, so I got some needle nose pliers and unwound part of the spring and shaped it into a new hook. I clipped it in place, put everything back together, started the pump on low and thankfully it worked!

Thanks for your help mas985

 

[mas985]

Glad it worked out.