Air Compressor Motor Struggling to Run

Thanks everyone for your input. Heading out the door now to do some checks. It's 19 deg F outside so I hope it goes quick! LOL
 
Brrr. It's cold outside! Checked everything suggested. There is no discoloration on the spade connectors at the motor terminals. I pulled each connector (black, white and green) and reconnected them. Didn't notice any corrosion on the terminals either. Visually inspected each of the capacitors and didn't notice any bulging or leaks. Measured the input voltage at each motor terminal (white to ground and black to ground) and each measured 120-122 vac with the motor trying to run. This morning it won't start even with the tank outlet open to atmosphere. It's cold but I'm leaning towards a bad motor.
 
That might be the centrifugal switch that's inside the motor thats the initial problem but now that it is no longer trying to start you might have burned up the start cap circuit. If the start cap is still ok you can usually get them moving again on their own by gently cleaning that centrifugal switch contacts.
 
Latinrascalrg1 said:
That might be the centrifugal switch that's inside the motor thats the initial problem but now that it is no longer trying to start you might have burned up the start cap circuit. If the start cap is still ok you can usually get them moving again on their own by gently cleaning that centrifugal switch contacts.
Click to expand...

I'll check that out. My next step is to remove the motor and bring it to an electric motor shop and have them test it.
 
Could also still be the capacitors. Just because they don't show visual signs of being bad doesn't mean they are good. Remove them from the circuit to test.
Remove the belt and see if the motor will run with no load. If it hums but doesn't start give it a spin by hand and see if it starts. If it does either the start capacitor or centrifugal switch is likely the problem.
 
Some compressor motors don't have centrifugal switches, they are capacitor-run types. Not sure what yours is
mark
 
That's true, and there are motors that have neither switch or cap, but they usually aren't used on compressors of this size
My brother had a Thomas dual tank compressor that was a cap-run type motor- it basically vibrated itself to pieces and the bearings fell out
The capacitors never gave any trouble though :)
The OP mentioned his motor starts off well but slows after a while- sounds suspiciously like a cap-run motor symptom
 
Last edited:
If you can check the windings on the motor with a meter on resistance you can see if they all ave the same resistance, if not close then could be bad winding.
 
You must log in or register to reply here.
Back
Top