Tools, Sharpening and Power Machinery - air compressor blows house circuit breaker

i have a craftsman 33 gal oil-less 15A air compressor that is about 2 years old and it has started blowing the 20A circuit breaker in my 1 year old house. cant figure out why a 15A motor is blowing a 20A fuse? no other equipment is plugged in the same circuit when this is happening, the compressor is about 8 feet from the fuse box.

sears wants to send a tech out to diagnose the problem for $80! they will not offer tech help over the phone or in person.

someone had mentioned something about a bad capacitor but i really dont know how to go about diagnosing this problem or replacing the capacitor? any help would be appreciated!

There could be a few different causes of this.

One is that the unloader mechanism is not functioning causing the compressor to start against high pressure.
Each time the compressor restarts there is a puff of air that will relieve pressure against the compressor.
A way to help diagnose this is that it would start normally when you first start it but begin tripping the breaker upon restarting while in use.

Second is a defective motor.
The capacitor or starting switch could be gone but you would need to venture inside the motor to find out.

Third could be a weak breaker but is not too common a problem when you only occasionally use the compressor.

At what point in the compressor cycle does the breaker trip?

Each time the compressor restarts there is a puff of air that will relieve pressure against the compressor.
Each time the compressor STOPS.

At what point in the compressor cycle does the breaker trip?

the compressor is tripping the breaker at startup, immediately after i flip it on, the motor doesnt even start.

Can you manually turn the flywheel/pulley?

That would indicate that the problem is with the motor.

The capacitor could be easy to change if you knew how and it is also possible to test it.
To check it you would need a multi meter and have an idea how to use it.

It is possible to visually inspect it to look for overheating or a slight fluid discharge near the connectors.
It is also possible the starting switch is gone or the motor windings are burnt.

Even possible is that the pump is seized and the motor does not have an opportunity to spin over.

This might be a bit much to diagnose if you are not at least a bit familiar with this type of troubleshooting.

It might be less expensive to troubleshoot if you were to bring it to a repair shop yourself.
And, Sears does not have to look at this for you.
A motor shop familiar with compressors could look at it for you.

I read this with interest, the people here know their "beans".
I am not an electrician; but a 15 amp motor breaker should be used, not 20 amp, in my opinion..
I'd say that the motor is drawing too much current for too long a time..so the breaker must trip - good thing too..
If we had a $5,000 commercial unit, $80 for a service call would be reasonable; for a homeowner like me, the same $80 from Sears is outrageous; but they must charge something..
We are damned lucky that there are KNOWLEDGEABLE people willing to give free but valuable advice over the Internet.

thanks Greg, looks like i'll be paying someone to diagnose the problem...
is it ok to disconnect the motor from the tank and take that in? i dont have anything to haul the whole thing down there.

It would be better to somehow get the whole thing to the repair shop.

They would likely be able to diagnose the problem with just the pump assembly but if you did get them to repair it the parts you leave at home would be needed to test it.

Whatever price they give you carefully consider what the unit is actually worth and don't forget how long it lasted in the first place.

If you read previous posts on the subject of compressors you will realize that the type you have is not that highly regarded.

Also, there is a sticky at the top of this forum about compressors.

thanks Greg, yes i read the sticky, if only i had known i wouldve bought a regular compressor and not an oilless one...i paid $200 for it used about 2 years ago, so total 4 year old compressor. if it costs more than $100 to fix it im tossing it.

I have a 25 gallon Craftsman that is doing the same thing. I suspect the capacitor, but am not totally sure. Someone mentioned that it could be tested with a multimeter. Which scale on the meter would I use to test ?

Also, Sears parts does not list a capacitor with that unit, although it has two of them mounted externally on the motor. Do any of you guys know where I can find replacements ?

I am in the Houston Texas area. Any help would be appreciated.

I'm going to resurect this puppy and see if I can get anywhere with it since it's the closest I've found to my problem.

I have a Craftsman 25 gal with the oil-less pump. I checked out the sticky to realize that I should have bought a cheaper one since it's a POS anyway.

It's it's pretty much doing what has been described here. Except it does start up initially. It starts but runs very sluggishly for a couple of seconds. Then the breaker blows.

Some more background: I had it on an outlet that had other things on it (mostly lights). It was plugged in with an adapter for a non-grounded outlet. Initially it was working fine but then it tripped the breaker and has been acting like this since.

I'll check out the capacitor if I can find a torx bit long enough to take this silly shroud off. Any other ideas on what I should check?

Thanks
Ray

I'm working in homeowners houses quite frequently, lugging in a little 1 1/2 HP Emglo compressor. Every once in a while, depending on where I plug it in, it will do something similar, 998Pilot... and I always assumed it was because it was on an outlet that was at the end of a long run of 14-2 romex... a long ways from the breaker box... because it will do the same thing as if I had plugged it into one of those small diameter extension cords- (chug... chug... chug.... click!) or maybe it was on a breaker that was getting weak (if there is such a thing!)

If you can try it on a different circuit, or have a bigger extension cord, I'd try that. If you have no problems, I bet there's nothing wrong with the compressor in this instance.

Yeah...I've tried it on different circuits. Even the one that my washing machine is on (supposedly the only thing on it). The thing is, I tried it on a new house when I PCSed back to Texas and the same thing was happening.

I'm gonna take it to the craft shop here on Fort Rucker tomorrow to see if they have a torx bit long enough to reach the screws on the shroud since I don't have any that long & narrow. While I'm there, I'll see what thier plugs do. I imagine it will bahave similar, but I'll give it a whirl.

As soon as I can get that shroudh off though, I'm getting my multitester out.