25 years ago I bought and installed a Sears 3-wire well pump and controller. It
is 1/2 HP and made for 230 VAC. Lately the controller has been acting up,
making buzzing noises, etc. So I decided to replace it. I bought the latest
1/2 HP pump controller from Sears, but I don’t know if it is right for my pump.
The specs are off and there are some other differences.
The original pump controller advises that the winding resistances for the pump
motor should be:
Red to Yellow: 5.2 Ohms (the Start winding)
Black to Yellow: 4.0 Ohms (the Run winding)
And sure enough, when I measure my pump with the power disconnectedf, my pump is
very close to these measurements. But the specs on the new pump controller call
Red to Yellow: 18.5 Ohms (the Start winding)
Black to Yellow: 4.7 Ohms (the Run winding)
The Run winding is close enough, but the Start winding is way off. Also, the
original controller has two capacitors: a Run capacitor and a Start capacitor.
The new controller has only a Start capacitor, which I measured to be 62 uF.
Both controllers have a relay to switch the windings and the capacitor, but I
find it hard to believe that a pump designed for a running capacitor can run
just fine without one, and the big difference on the Start winding specs has me
Before I replace the controller and risk burning out my pump, I would like to
know if anyone can shed any light on these differences.