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AO Smith Air Compressor Won’t Start

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Need some input on figuring why compressor won’t start.

Bought a brand new but never used air compressor from an individual, three years old, never hooked up. They bought it for their home shop before adding electricity, finally got power out there and decided to go larger. It’s a 60 gallon, oiled, AO Smith 208-240V, 15 amp motor, whole compressor was still in the plastic wrap on the pallet with tags hanging from it. Stored in a dry shop the whole time.

Ran a new dedicated 20 amp circuit, 12/2, decided to use an outlet and pigtail in case I wanted to use the circuit for something else. Wired it up, turned it on for the break in procedure for 30 minutes with drain valve open, turned it off. Closed the valve, turned it back on about 15 minutes later, filled up the tank and cut off at the correct pressure, 150psi, seemed to run flawlessly both times. Hooked up a blow nozzle and started to release air, wanted to see if it kicked back on at the low setting (90psi), never did, I bled all the air out.

Thought there might be an issue with the pressure switch, checked all the connections, checked for power coming to the switch, got 120v on each leg, so there is power getting to the switch. Then bypassed the switch by wiring straight to the motor, (just to check it, was not going to let it run to fill the tank), nothing. Power is going to the motor but nothing happening. No hum, no click, nothing. Unplugged it to see if the the pump flywheel would spin freely, spins fine, no locking up or anything.

So now I’m thinking it may be something with the starting circuit on the motor? No idea why that would go bad after two starts but not sure what else it could be?

Thoughts and suggestions welcome.
See the page on checking a capacitor, and check your start cap.


Comments for AO Smith Compressor No Start
Jul 16, 2014
Problem solved
by: Anonymous

Pulled the cover on the motor, poor/loose contact. Reconnected power and it started right up!

Jul 15, 2014
No start
by: Buster Norris

After looking at the start cap, I would look to see if there is an overload reset button on the end of the motor, and look inside to see if there may be some varmints that have taken up house after sitting for three years, dirt daubers are notorious for getting dirt on the start contacts from their nests and not allowing the motor to start. Just a thought. Please repost the results if you get it started!

By Aidan Weeks

A passionate Mechanical Engineer with endless enthusiasm for fluid power - building off the back of over 18 years of high quality contribution and discussion stimulated by Bill Wade here at About Air Compressors. With both practical and theoretical experience in pneumatics and hydraulics, I'm putting my knowledge to work - and working my grey-matter through my research, assistance and publishing work here at About Air Compressors. Feel free to reach out any time! P.S. A HUGE shout out to Doug who really offers such great value to all visitors to About Air Compressors - once again, feeling like I'm standing on the shoulders of GIANTS by getting to work alongside such a great community

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