Help Me Troubleshoot My Air Compressor

[ARAMP1]

I have a Craftsman Professional model 919.184191 air compressor. It's a 60 gallon tank 7 HP single stage compressor. It's about 6 years old and it just flat out would not turn on the other day. So, I drained the tank ans started troubleshooting. Here is a list of some things that I've done, and now I'm not sure where to look next.

The electrical outlet works and pressing the overload reset button on the motor does not work.
Both the motor and compressor turn freely.
The pressure check valve was a bit dirty, but it still worked, so I cleaned and re-installed it.
I replaced the pressure switch since the other showed some signs of corrosion.

Now I'm kind of at a loss as for what to do next. Any suggestions?

 

[Fordum]

Does it hum? If so, then its a bad capacitor or internal centrifugal start switch.
If its completely dead, then electrically check the pressure switch or temp bypass it.

If there is a little lever coming out of the pressure switch going to a small air valve, and it hums but cannot start, then that little valve might be bad.
Some compressors have that little unloader that releases the pressure on the compressor when it turns off, so that it does not start under load.

 

[ARAMP1]

It doesn't hum at all.

 

[Fordum]

Then it either the pressure switch, the overload, or the motor is burned up. If you are sure the outlet is good.
My money is on the pressure switch.
You could move the power wires to the other side of the switch, bypassing the contacts, and plug it in briefly to see if it starts.
Got to go to a doctor's appointment, check back in after.

 

[nvrenuf]

Is the power cord good? Maybe the connections vibrated loose in the motor? I'm just guessing.

 

[Fordum]

OK, I'm back.
I reread what you posted, and I see where you replaced the switch. New never guarantees good, but its unlikely that two of them are bad. I know you said that you checked the outlet, but how did you check it?
With a meter or a load?
An outlet can check good with a voltmeter, but will not put out enough current to drive a load.
So, if you can, plug something into it to be sure.

Then, if you have a meter, put it across the two power leads at the motor side of the switch with it plugged in and turned on.
If you have power there at that time, then you have to move on to the reset button.
Try pressing it harder. Most of the time it should have some looseness about it if its not tripped.
If you can get to it, put a meter across its leads when the machine is plugged in and turned on.
You should not read any voltage across it if its good.

Heading back out, I'll check in when I get home.

 

[ARAMP1]

OK, I'm back.
I reread what you posted, and I see where you replaced the switch. New never guarantees good, but its unlikely that two of them are bad. I know you said that you checked the outlet, but how did you check it?
With a meter or a load?
An outlet can check good with a voltmeter, but will not put out enough current to drive a load.
So, if you can, plug something into it to be sure.

Then, if you have a meter, put it across the two power leads at the motor side of the switch with it plugged in and turned on.
If you have power there at that time, then you have to move on to the reset button.
Try pressing it harder. Most of the time it should have some looseness about it if its not tripped.
If you can get to it, put a meter across its leads when the machine is plugged in and turned on.
You should not read any voltage across it if its good.

Heading back out, I'll check in when I get home.

Yeah, I plugged my welder in and it fired right up, so I'm pretty sure the outlet is good. Plus, I've been using this outlet for several months with the air compressor.

Anyway, I'll have to check and see if my meter is good with 240V. I just got home from work and it's 0100, so it'll have to wait for tomorrow (later today).

 

[Fordum]

Anyway, I'll have to check and see if my meter is good with 240V. I just got home from work and it's 0100, so it'll have to wait for tomorrow (later today).

Tell me about it. Its 2 freaking 30 and I'm still hanging out here........

 

[ARAMP1]

Well, this is the damndest thing...I found an old AC (as in alternating current) gauge that I had bought about two years ago. I plugged in the compressor to troubleshoot if the motor was getting electricity. I turned the switch on and it fired right up. I don't even know what to say. It works and is building pressure as it should.

Thanks for all the input Fordum!

 

[Fordum]

That is probably going to rear up and bite you again one of these days. Sounds like maybe a bad connection in the power cord, or one of the wires going to the overload.

Look where its plugged in, and all around. If the cord is bad internally, its going to get hot. Make sure there are no papers or stuff close by that might burn.
Thats always a good idea, but be a little extra careful.

Next time it has run for a while, carefully feel the plug and the wire next to it to see if its hot.
Warm might be normal, but not hot.

Of course, that is assuming you are using some kind of molded plug. If its one that can be disassembled, then just take it apart and look for either a loose connection or signs of heat.