Air compressor won't re-start

[TurboAWDFanatic]

Sorry for the long post, just want to lay out the details to make it easier:

I have a Craftsman 25 gal 5.5hp (heh, yeah right) upright single piston oil free air compressor (model 919.165190). It starts up just fine when I first turn it on and it will run flawlessly to fill the tank to full capacity, BUT, when I use up air and the compressor tries to turn back on it just strains and eventually trips the breaker. It is plugged directly into the wall socket (no extension chord). I bought it as a floor model so there was no user manual with it. Was I supposed to run the compressor for 20 min with the valve open? It's an "oil free" type...

I *DO* hear a pressure relief when the motor shuts off, so there shouldn't be pressure pushing against the motor when its supposed to start up. I tried relieving pressure in the tank little by little to see when it would be able to start, and it can only start when there's less than 30psi in the tank.

Seeing that I use an impact wrench, air ratchet, and other automotive tools I'd like to have a compressor that can cycle back on to keep the pressure up. Any thoughts?

Thanks!

 

[mhoffm911]

Can't help you, but you CAN order the manual here:

http://www3.sears.com/

 

[bmwpower]

I had the exact same problem and resolved it in a thread somewhere on here.

The solution:
If the compressor is on it's own circuit (which it is), up the breaker size to the next size (allowed by code).

 

[Charles (in GA)]

While it is relieving the pressure on shutdown, it also could have a leaking check valve and this might be allowing tank pressure to work back into the head long after shutdown, causing this.

Charles

 

[5wndwcpe]

While it is relieving the pressure on shutdown, it also could have a leaking check valve and this might be allowing tank pressure to work back into the head long after shutdown, causing this.

Charles

That's my guess. Try disconnecting the compressor from the tank while the tank has a full charge. If you hear a short blast of pressure and the motor starts, that's your problem.

 

[Aceman]

A weak or undersized breaker is another possibility.

 

[ImportTuner]

Also try plugging it into a higher amperage circuit ... like not use an extension cord ..

 

[TurboAWDFanatic]

Thanks for the quick response!

That's my guess. Try disconnecting the compressor from the tank while the tank has a full charge. If you hear a short blast of pressure and the motor starts, that's your problem.

This checked out fine. No leaks, check valve must be okay.

I had the exact same problem and resolved it in a thread somewhere on here.

The solution:
If the compressor is on it's own circuit (which it is), up the breaker size to the next size (allowed by code).

Unfortunately, I live in a condo, not a house. The circuit breaker is at the end of the row of garages. I really have no way of telling what's on the circuit, nor do I think HOA would be happy with me swapping out to a higher rated breaker. =\ I've tried running the compressor w/ a pressurized tank at crazy late hours (3 to 4 am) to no avail, so I don't think its a matter of lights/stereos/ect being used in other garages on the same circuit. I suppose the breaker could be weak like Aceman suggested. I suppose it could also be a result of the circuit box being so far away from my garage.

This may be a long shot (sorry, new to this), but is there any capacitor type unit that I could plug inline between the compressor and the wall that could store enough juice to get the motor running? I know these exist for sound system amplifiers, but is there any (affordable) application for my situation? Or is that barking up the wrong tree?

 

[wilbilt]

You could wire in a magnetic starter, but if it is a voltage drop issue, it probably won't help.

Try connecting a voltmeter to the outlet the compressor is plugged into to see what the voltage is while the motor is trying to start.

 

[bmwpower]

If you live in a condo and you're not allowed to mess with the electrical, you may be stuck. Is that circuit GFCI protected? Without the ability to make changes/test things with the electrical, there's not much you can do.

 

[trovato]

If the compressor strains and then "eventually" pops the breaker, I don't see how this is a problem with the breaker. Sounds to me like a larger breaker will just let it strain longer before tripping, hopefully still before the house burns down. Can you take the compressor somewhere else to test? I would think that would potentially eliminate power as the problem.

 

[russlaferrera]

What does the motor data plate say? How many amps does motor draw?

You may be electrically challenged.

An electric motor requires 1 1/2 times the power to start.

 

[5wndwcpe]

I still don't think it's an electrical problem. The motor starts fine with no pressure in the tank, won't start with the tank fully charged and yet it starts if the pressure drops below 30 psi. It's gotta be the valve.

 

[goodfellow]

I still don't think it's an electrical problem. The motor starts fine with no pressure in the tank, won't start with the tank fully charged and yet it starts if the pressure drops below 30 psi. It's gotta be the valve.

I agree on the valve. I "burned up" two Sears oilless units in my day. One went because of a bad motor, the other was because of the valve.

To eliminate the electricals, I would take it to a friend's house and plug it into a higher amp circuit. That would definitely put the issue to rest.

 

[Aceman]

^^^Did you guys read post #8. He already checked the valve! He has it plugged into a condo circuit with who knows what else sharing on the same circuit. Condo's are built cheap usually, it's probably #14 wire on a 15 amp breaker. A long circuit ran with small wire makes for a lot of voltage drop at startup, then it really starts pulling amps. Only one way to check that's easy, plug it into a known good circuit, as a few people have already said.

 

[TurboAWDFanatic]

To eliminate the electricals, I would take it to a friend's house and plug it into a higher amp circuit. That would definitely put the issue to rest.

I'm planning on doing this, just don't know of a good place to try yet. I'll keep you updated.

 

[5wndwcpe]

^^^Did you guys read post #8. He already checked the valve! He has it plugged into a condo circuit with who knows what else sharing on the same circuit. Condo's are built cheap usually, it's probably #14 wire on a 15 amp breaker. A long circuit ran with small wire makes for a lot of voltage drop at startup, then it really starts pulling amps. Only one way to check that's easy, plug it into a known good circuit, as a few people have already said.

Yes, I read the post. But he didn't say if the motor started or not with the valve out of the loop, so the results aren't clear. If it's an electrical problem, then explain to me why the motor starts if the pressure drops below 30 psi.

 

[TurboAWDFanatic]

Yes, I read the post. But he didn't say if the motor started or not with the valve out of the loop, so the results aren't clear. If it's an electrical problem, then explain to me why the motor starts if the pressure drops below 30 psi.

Okay, I did some further testing. I pressurized the tank to about 90psi and turned it off (it made a short*hiss* sound like it should when i shut it off). I separated the line from the motor to the tank: no pressure loss. I switched the motor on and it started up instantly (spitting air out of the disconnected hose).

I then hooked the motor back up to the tank (still pressurized to 90psi).

I then hooked up my volt meter to the outlet.
All lights off except one fluorescent: 121-122v
Shop lights on: 120-121v
With only the fluorescent light on I tried to start the motor with the pressurized tank: DROPPED TO 69V and strained.

I switched the motor off before it tripped the breaker. I tried all of this twice to be sure of the numbers.

 

[chavist93]

Can you try it somewhere thats closer to the breaker? It sounds to me like youre on a long run of wire to the breaker. I deal with this every day using portable compressors at work (construction). If we try to run the compressor on too long of an extension cord to get it closer to the house it will sometimes do the exact thing yours is, especially in cold weather. Then we take the compressor and plug in directly at the breaker box and it starts right up every time.

 

[TurboAWDFanatic]

Can you try it somewhere thats closer to the breaker?

Can't do much save lugging my compressor over to an outlet next to the breaker. Might get some weird looks from the neighbors, though. (Just moved here, don't want to piss anyone off)

I'll find some place to try it soon and come back with the results.

 

[5wndwcpe]

Okay, I stand corrected. It sounds like the motor doesn't ramp up fast enough to overcome the relief valve, hence the overload. Perhaps try a heavy ext. cord to a different outlet in the house ? I know it would make the run longer, but it might allow you to tap a less "sensitive" circuit.

 

[TurboAWDFanatic]

Perhaps try a heavy ext. cord to a different outlet in the house ?

Exactly my thoughts this morning. It's a fairly mobile air compressor so I'll try moving it over to an outlet inside my condo close to the circuit breaker. (I have better control of the electrical in my actual condo, its just the garages that are all running off a panel on the exterior)

I'll update tonight.

 

[Vicegrip]

Capacitor, start winding or start switch might be bad. If the cap is bad or the start winding is not energized the motor will try and start using the run winding only. The run winding has little torque at speeds under 70% or rated. Even if the cyl head unloader is doing the right thing the motor will feel the pressure in the tank with the first pressure stroke. Unless the start winding is in play the motor will not have enough torque to spin under the load. If the tank has no pressure then the motor is free to start with little load as the first pressure stroke is not against 100 or more PSI.

I would test the capacitor and if you don't have a cap tester replace the cap. sometimes when they fail they get fat like a frozen coke can. They are $5 to 10 bucks. If still no go look at the centrifugal start switch that is most often in the opposite end bell housing. It will look like a small ring arond the shaft end between the stator and bell housing. It will have a weight or two and some copper looking spring contacts. The contacts should be closed with the motor at rest and they should be clean and not all burned up looking or stuck. You can also test the start winding. Use the start switch to figure out the start and run winding leads and see if the start winding is open. you might have to remove the opp end bell housing to inspect the start switch and test the windings. If so make a set of marks that span the winding case and bell housing so you can line them back up. 4 long bolts hold the ends to the winding case.

 

[TurboAWDFanatic]

Thanks for the insight, Vicegrip. I'm leaving town for a week but I'll look into things and then post a followup if I find out what's wrong.

 

[TurboAWDFanatic]

Alright...finally, the resolution to this problem.

I've barely had a chance to even flip the lights on in the garage this month, much less do any work. This weekend I *finally* got the time to grab some heavy extension chord and test the compressor on a known good 20amp circuit. What do you know? Works like a charm! Starts up just fine even w/ 100psi already in the tank. Guess the garage circuit is just too weak to handle any heavy loads.

Thanks to everyone for the input. Though it ended up being a simple stupid issue, I learned a lot from everyone's comments. =)

 

[wilbilt]

With only the fluorescent light on I tried to start the motor with the pressurized tank: DROPPED TO 69V and strained.

Bummer. A long run on a shared circuit, I'd guess. Not much you can do in a rental situation. Maybe a complaint to the building management?

I wonder how many other tenants are running freezers, etc., in their garages? What's the policy on powering "equipment" in there?

 

[TurboAWDFanatic]

Bummer. A long run on a shared circuit, I'd guess. Not much you can do in a rental situation. Maybe a complaint to the building management?

I wonder how many other tenants are running freezers, etc., in their garages? What's the policy on powering "equipment" in there?

Not sure on the policy. Have to dig out the paperwork. No worries, though, found an unused outlet next to the hot water heater which is in an enclosure right next to my garage. It runs off a 20amp in my condo. Works fine now, just have to run about 10' of extension chord when I use the compressor.