When was the last time you drained the water condensate from the tank?

 

Water in the tank would have no effect. Humming instead of spinning up at startup point to a start circuit problem… either centrifugal switch or capacitor. Capacitors are easy enough to test with a cheap multimeter.

Cheers,
Brad

 

I drain the tank after every use.

I went back out an hour after I posted this and now it cranks on. I guess it was thermally overloaded somehow? I guess I will have to see if this continues to happen then test the capacitors and the centrifugal switch if it does.

Thanks Brad. And YouTube.

 

Glad it's working again, but when's the last time you blew the dust out of that thing? I realize you said you were in the middle of a paint job, but dang, that's a LOT of white dust INSIDE that motor and all over it. A buildup of dust can also cause overheating.

 

You need to keep the windings of the motor free of dust build up to help the cooling. Also keep that air intake filter clean. Dirty filter puts more load on the pump and motor. Caps can get weak and not do their job without showing any bulging.

 

I'd also remove the belt and see how the motor does without the compressor part loading it down. If motor spins up good, might be piston issue. Obviously, oil levels need to be checked. Once belt is off too, try turning the pulley on the pump to feel the level of resistance to figure again if its the piston part.

 

I'm thinking with MrUnix.

Most compressors do have an 'unloader' that allows the motor/pump to get up to speed before starting to compress air. If the unloader is stuck, the motor may not have a chance to get things spinning before tripping the breaker. Of course you would observe the motor starting to turn if this was the case, so I'm thinking start cap/cent. switch

 

Once you diagnose the issue, everything about that compressor can be repaired or replaced, and as long as the tank is in good condition, it's almost certainly worth fixing.

In addition to the good suggestions so far, you might want to unplug the unit and inspect the contacts in the pressure switch. My experience is that those contacts are optimistically rated, and if they're not conducting enough current, it could affect startup. I am not impressed with the pressure switches in most compressors, but that doesn't mean it's your problem, just something that is easy to check.

 

Check it well, and clean all the "shmutz" from the surface. No tellin' how much crap is in the motor.
Bill

 

^ +1, half the compressors I've repaired have burned contacts and conduct poorly if at all.

 

What was the temp in your shop? How long had you been spraying before the compressor stopped? It's very possible nothing is wrong except the dirty motor. These light duty compressors can overheat in a warm/hot shop with a spray finishing duty cycle. Clean out the motor windings. It's also possible the pressure unload stuck, which dumps pressure at the discharge line so the motor doesn't have to start against head pressure. It's possible but not likely the cap is bad - not old enough. Report back what you find.

 

Did you say that it tripped the breaker for the receptacle or just the breaker on the compressor? If both, you might want to get a meter and see how many amps it is pulling to see if it is exceeding the specs on the motor. If it were just the breaker on the the compressor, it could have just overheated because of continuous use but the one for the receptacle should not trip unless perhaps you had several tools running at once plugged into the same circuit and exceeded the total amperage for that circuit, which can happen easily when the motor starts up.

...And if you have a compressor, use it to blow the dust out of it every now and then. Sorry, I couldn't resist. ;-)

 

Thanks guys. The compressor actually is not dirty at all inside the motor. I paint 30 feet from the compressor and that is paint dust landing on the surface. Didn't see anything inside the motor, just on the outside frame. It was extremely hot that day and I had been painting for a half hour and it was running a lot. I had a 3/4 horse exhaust fan and this compressor running on a 20 amp circuit. I was just surprised because it never did this previously. I will check the filter and clean it and see how that plays out. Hopefully it was just a fluke!

 

Breakers get weak, too.