Have a hot tub 2.5 years old one of the motors is 2 speed. When I push start on that one it just hums. Could it be just the capacitor. If so how can it be checked ?
Two-speed hot tub motor hums but doesn’t run
hot-tub
Related Solutions
Not sure if this helps but I ran in to something similar. If your tub gets too hot, it might go past its heat limit and stop heating all together. There should be a high limit reset switch that you'll need to hit to get it heating again. Just adjust the temperature setting so it doesn't hit the limit. Mine was showing that it was heating on the top panel, but wouldn't start heating until I reset the limit switch. I had prior work done to it and the tech cranked the heat all the way up to test something and I overlooked it once we got it going again.
After pulling the motor out (which required draining the spa and disconnecting the PVC connections) and removing the cover, I found another capacitor. Googling the part number indicates that this is a start capacitor. It helps the motor start.
The motor also has a capacitor on the outside, and it's the run capacitor. That's the one that was replaced first.
After replacing the start capacitor, the motor started and is running.
http://en.wikipedia.org/wiki/Motor_capacitor
It turns out that Spa/hot rub AC motors like this have both a start and run capacitor, as do blowers on forced air furnaces and air conditioning units. If an AC motor like this won't start, there's a good chance it's the start capacitor. The start capacitors tend to fail eventually, the run capacitors last much longer, apparently.
My spa motor
Start capacitor
Run capacitor
Best Answer
Many single phase motors use a start capacitor. If it fails the motor can hum without starting. Sometimes they puff up and are obviously broke. If it appears OK visually then you will need to test it.
To test a capacitor you will need to disconnect it from the motor. If not use a digital multimeter set on resistance connected across the terminals of the capacitor. Initially it should read extremely low and the resistance should climb as the capacitor charges. Reversing your leads should yield the same result. If you get these results, the capacitor is good.
Otherwise a failed capacitor will read zero or infinite resistance.
If it is not the capacitor, it could be the pump motor is seized or the piping is plugged.
Good luck!