I have a century B984 2 speed pump. It runs fine on high but only humms on low. I can run it on high and switch to low and it will run or I can turn it on low and manually spin it and it will run on low. I don’t see a start capacitor only the run capacitor on the side. Any idea what I should check?
A pool owner had a similar situation happen back in June. He replaced the capacitor and it didn’t solve the problem. According to the motor manufacturers we contacted, it was likely the centrifugal switch at the back of the motor.
Here is a link to that thread. https://www.inyopools.com/forum/thread/hayward-superpump-dual-speed-wont-work-on-low-speed/