Kobalt Compressor help. (Repaired)

[Pucman1]

I got a used 2008 or so Kobalt 26 gallon stand up compressor. It runs for about 20 or so seconds building pressure but then pops the circuit breaker on the back of the electric motor. Switch it off the unloaded clears fine, holds pressure fine(no leak down). All the filters are clean and inlet pipes no obstructions. Not sure where to go next. Any help.
I was thinking about replacing the circuit breaker….all the wiring looks perfect, all tight.

Chime in, how can I get it running?

 

[RTM]

Has it worked prior, or is it new to you?

115 or 230V?

How much pressure before it craps out?

Several threads in the recent past about 230v compressor being run on 115.

Compressor 230v with 115v plug?

I recently picked up a free Craftsman 4HP compressor which I was told was working fine and it runs for about a minute before bogging down to a standstill and then trips the thermal switch on the motor. The guy I got it from said he never actually used it but the neighbor who gave it to him used...

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Older Craftsman 1.5 hp air compressor, 240v right?

I picked up this air compressor from CL free stuff a while back, but haven't used it because I didn't have the right outlet for the plug. This needs a 240v outlet such as this, right? https://www.amazon.com/gp/product/B000FPDKOI?tag=atomicindus08-20 You can see the plug sitting on top of the...

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[The Cobbler]

what is the amp draw of the motor, and what amp service are you running to it?
you running an extension cord?

 

[Pucman1]

It was working, my buddy lent it to someone, came back and wasn’t used for a bit….now this! Here is the tag for the unit! No extension cord, plugged direct to an outlet 20a circuit 3 feet from the panel.

 

[johnre]

Is the oil level OK in the crankcase? (I'm assuming it's not oil-free compressor here)

What happens if you just release the air and let it run, will it continue running?

Is the motor warm when it trips out?

Any way you can measure the voltage and the current draw close to the motor at the pressure switch?

 

[Pucman1]

Is the oil level OK in the crankcase? (I'm assuming it's not oil-free compressor here)

What happens if you just release the air and let it run, will it continue running?

Is the motor warm when it trips out?

Any way you can measure the voltage and the current draw close to the motor at the pressure switch?

No oil it is oil free, motor is not warm but the tube at the top of the pump that run downs to the tank get warm quickly.
Hmm will have to see where that switch is….
I will test the just letting it run theory later today.

 

[The Cobbler]

the tube that goes to the tank gets hot, that's normal

 

[Pucman1]

No oil it is oil free, motor is not warm but the tube at the top of the pump that run downs to the tank get warm quickly.
Hmm will have to see where that switch is….
I will test the just letting it run theory later today.

Is the oil level OK in the crankcase? (I'm assuming it's not oil-free compressor here)

What happens if you just release the air and let it run, will it continue running?

Is the motor warm when it trips out?

Any way you can measure the voltage and the current draw close to the motor at the pressure switch?

Not sure how to get the draw on this because by the time I turn it on and get the leads on it, it has cut off and tripped the breaker.

 

[The Cobbler]

when it starts, does it sound normal, or is it bogging?
can you turn the pump easily by hand (without power attached)?
have you tried to run it with the discharge line removed so the compressor is just venting to atmosphere?
are there capacitors on the motor? they could be bad .
I assume pressure is getting in to the tank and not just building int he discharge line?
just trying to think of possible causes .

 

[Pucman1]

when it starts, does it sound normal, or is it bogging?
can you turn the pump easily by hand (without power attached)?
have you tried to run it with the discharge line removed so the compressor is just venting to atmosphere?
are there capacitors on the motor? they could be bad .
I assume pressure is getting in to the tank and not just building int he discharge line?
just trying to think of possible causes .

Sounds normal, have not ran it with the line disconnected yet. Two capacitors on top of the motor. See photo …

 

[Pucman1]

Yeah I ran it until it kicked and reset a couple different times and built pressure up to about 50 psi and has not dropped yet

 

[Pucman1]

Yeah I ran it until it kicked and reset a couple different times and built pressure up to about 50 psi and has not dropped yet

Ok so line disconnected it keeps on running, no problems…..took the line off up until the check valve on the tank and it is clear….
This is crazy…. Maybe the check valve, but why would it kick the circuit breaker on the motor?

 

[johnre]

I ran it until it kicked and reset a couple different times and built pressure up to about 50 psi and has not dropped yet

Too much conflicting information here - with a 26 gallon tank and a 120 V motor, you certainly aren't getting the pressure up to 50 psi in 20 seconds.

Get a decent pressure gauge that you trust, start from zero pressure, and start it up. Then tell us what the trusted gauge says, and how long it was before it tripped.

 

[Pucman1]

Too much conflicting information here - with a 26 gallon tank and a 120 V motor, you certainly aren't getting the pressure up to 50 psi in 20 seconds.

Get a decent pressure gauge that you trust, start from zero pressure, and start it up. Then tell us what the trusted gauge says, and how long it was before it tripped.

You are correct! It will run for about 20 seconds before it pops the circuit breaker on the back or the motor. If I keep resetting it and running it continues to build up pressure, I have ran it up to 50 psi to check the tank and valves. The gauges are correct, the unloader valve does its job when I switch the power off. It seems like a pressure issue more than an electrical item. I am going to pull the top of the cylinder a part to inspect the air compressor pump valve plate kit. If that is ok, I’ll probably move to checking the tank valve. I am trying to eliminate buying a bunch of unnecessary parts…..
The circuit breaker is 25 bucks, the pressure regulator manifold is 74 bucks….
I am trying to go though the process like Kobalts troubleshooting guide. I appreciate all the suggestions, definitely want to save this one because it is so clean… it has a lot of life left in this one….

 

[dchawk81]

If it continues to build pressure after you reset it, is the switch bad?

 

[Pucman1]

If it continues to build pressure after you reset it, is the switch bad?

That is the question? Trying to figure out what is tripping it. If I loosen the tube that goes from the motor down to the tank, it will keep on running.?

 

[Citation]

Couple of questions:

1. Have you verified the capacitors are good?
2. Have you checked the centrifugal switch on the end of the motor shaft (shown in your picture)

Typically a motor throwing a breaker will be due to overloading when either the caps are bad or the centrifugal switch doesn't work correctly which prevents the motor from switching from the start wiring to run wiring. Another possibility is the check valve is bad and you are building up more pressure in the line than the compressor can handle. I think that one is less likely.

 

[Pucman1]

Not that good with the electrical stuff. How do i check the capacitors, they look intact and are cool to the touch! How do you tell if the centrifugal switch is bad! I would think if the input pipe disconnected from the tank and the motor keeps on rolling for minutes that those would be good!
I am more leaning to a pressure issue!
Time and Money I will figure it out

 

[RTM]

I would think if the input pipe disconnected from the tank and the motor keeps on rolling for minutes that those would be good!

If the compressor is just pumping air, not compressing it into the tank, its not doing nearly as much work, and the workload is not building over time, so the motor is not working as hard. You might be eliminating the increasing amount of work. Can't easily think of an easy way to replace your downstream loading for an alternate way to test.

Don't recall this being asked. Do you have a second outlet you can run it from? Maybe your breaker is bad?

 

[Citation]

Bad wiring certainly could be an issue. As the compressor works against a higher tank pressure the list on the motor increases. That results in more current draw. If you have questionable wiring in the wall the voltage drops which actually results in more current draw and the motor things trips. Certainly worth a look.

 

[TigerDude]

I think the likely cause is a bad overload on the motor. If you were drawing too many amps this would pop your house breaker. Try running it at low pressure, the low will be much lower, see how it draws if you have a clamp-on you can use. You could just have a hard-to-turn motor or compressor that overloads the motor.

 

[Pucman1]

If the compressor is just pumping air, not compressing it into the tank, its not doing nearly as much work, and the workload is not building over time, so the motor is not working as hard. You might be eliminating the increasing amount of work. Can't easily think of an easy way to replace your downstream loading for an alternate way to test.

Don't recall this being asked. Do you have a second outlet you can run it from? Maybe your breaker is bad?

Yeah I have run it off a couple different circuits in my garage… same result!

 

[Pucman1]

I think the likely cause is a bad overload on the motor. If you were drawing too many amps this would pop your house breaker. Try running it at low pressure, the low will be much lower, see how it draws if you have a clamp-on you can use. You could just have a hard-to-turn motor or compressor that overloads the motor.

The motor is actually pretty easy to turn by hand! Clamp on? Not sure what you mean there

 

[Pucman1]

Bad wiring certainly could be an issue. As the compressor works against a higher tank pressure the list on the motor increases. That results in more current draw. If you have questionable wiring in the wall the voltage drops which actually results in more current draw and the motor things trips. Certainly worth a look

 

[Pucman1]

I ran it at my friends house on two circuits and my house on 3 circuits one of which is 3 feet from the panel… same result.

 

[The Cobbler]

I don't think it's a bad check valve based on the tank is building some pressure .

 

[The Cobbler]

It is possible the reset is weak . If are you able to source one for not a lot of $$$ it may be worth trying that .
the clamp on meter suggested is a meter that clamps on to a hot lead & measures the amp draw while the motor is running

 

[Pucman1]

It is possible the reset is weak . If are you able to source one for not a lot of $$$ it may be worth trying that .
the clamp on meter suggested is a meter that clamps on to a hot lead & measures the amp draw while the motor is running

Ok circuit reset is 25 or so bucks…. Might they that first

 

[Citation]

Have you looked at the centrifugal switch? Does it move freely. It should have some weights that pull against springs once the motor starts turning. With the back cover off you might be able to see the movement. If it doesn't actuate (contacts welded closed?) then your motor would never disengage the starter wiring and may trip as the speed builds.
Overall that motor and compressor look very clean so I would have trouble thinking you have a serious issue.

 

[Pucman1]

Have you looked at the centrifugal switch? Does it move freely. It should have some weights that pull against springs once the motor starts turning. With the back cover off you might be able to see the movement. If it doesn't actuate (contacts welded closed?) then your motor would never disengage the starter wiring and may trip as the speed builds.
Overall that motor and compressor look very clean so I would have trouble thinking you have a serious issue.

Yep that switch is working correctly. I clearly see it pull the contact over to switch to the working capacitor and with out the load it will run until I shut it down.
I also pulled the top of the cylinder apart and checked the valve plate assembly, it barely looks used. I think at this point I’ll bite the bullet and order the pressure regulator manifold.
We shall see …..!

 

[Citation]

The pressure regulator manifold is on the output side of the tank. That shouldn't be your issue.
So far the check valve (tank inlet), the motor parts (capacitors, cent switch) or the circuit breaker on the motor are your most likely failure points.

 

[The Cobbler]

The pressure regulator manifold is on the output side of the tank. That shouldn't be your issue.
So far the check valve (tank inlet), the motor parts (capacitors, cent switch) or the circuit breaker on the motor are your most likely failure points.

I agree, but I also put the check valve low on the list as it does seem to allow air in , and I would expect the motor to bog a bit (before the thermal pops) if it was over pressuring

 

[hefnerconstructionlc]

I think you need to watch a YouTube video on how to test capacitors and test those first. Then you can move on to more difficult diagnostic testing on the motor.

 

[OccupantRJ]

A clamp on amp meter will help eliminate if the motor is overloaded. This is a primary diagnostic tool for me, and solves a lot of guessing, money, and parts cannon firing.

 

[Pucman1]

I think you need to watch a YouTube video on how to test capacitors and test those first. Then you can move on to more difficult diagnostic testing on the motor.

Yeah I need a meter the will read micro ferrets and I don’t have one!

 

[Pucman1]

The pressure regulator manifold is on the output side of the tank. That shouldn't be your issue.
So far the check valve (tank inlet), the motor parts (capacitors, cent switch) or the circuit breaker on the motor are your most likely failure points.

Circuit breaker replacement is on the way. Reaching out to see who has a meter that reads micro ferrets …. Next

 

[OccupantRJ]

If you have a local electric motor shop, run the capacitor by there and get them to test it. Buy a replacement while there if needed. My price at the shop is equal to Amazon, and in my case, a 15 minute trip. I work on a lot of various machinery, so I bought a devoted capacitor tester on Amazon for $30.
microfarad.

 

[dchawk81]

Circuit breaker replacement is on the way. Reaching out to see who has a meter that reads micro ferrets …. Next

 

[Meursault74]

 

[Steve_P]

Don't tear into the compressor pump just yet...

Edit- too late.