Need Help troubleshooting my air compressor

[mlitt12345]

Hello all, went to my shop this afternoon started doing some sanding and noticed my cfm was getting low and my compressor didn't kick on. 1st thing I checked was the breaker then the circuit breaker on the motor all is good there. I did some more troubleshooting and checked contacts on the switch then bypassed the switch all together by wiring directly to the motor still would not come on. I think it may be a capacitor. It is a 2yr old Campbell Hausfeld VT6275 3.2 hp 60 gallon air compressor, looking for advice on how to check the capacitors and if there bad any suggestions on where to buy them at. Here are a few pics thanks for any help.


Mike

 

[larry_g]

Most caps will have a vent that blows out when they fail. Check the start cap. They can be had at most any pump, appliance, motor shop. Even may find on at the big box if they have a pump section. Also have you checked for a overload on the motor, red button?, that has pop'ed? It may also have a thermal overload that has failed. Do you have a meter to check continuity?

lg
no neat sig line

 

[mlitt12345]

Most caps will have a vent that blows out when they fail. Check the start cap. They can be had at most any pump, appliance, motor shop. Even may find on at the big box if they have a pump section. Also have you checked for a overload on the motor, red button?, that has pop'ed? It may also have a thermal overload that has failed. Do you have a meter to check continuity?

lg
no neat sig line

The red button on the motor has not tripped, I do have a ohm meter just don't know how to check the capacitors. I have also ruled out the pressure switch being bad by bypassing it and ran power straight to the motor.

Mike

 

[yasha32]

caps store a charge, so if you can get them charged up you can disconnect the power source and see if they will unload that charge. be advised that cap looked burly, itll hurt (injure, etc etc) if it hits you.

 

[larry_g]

With an ohm meter you can check a cap roughly. Disconnect the cap and discharge it with a screwdriver across the contacts. Now check the resistance. You should see the resistance climb from 0 ohms to infinity or near. Now reverse the leads and it should do the same. If it does not change and shows either open or shorted then it is bad, it is the changing resistance that shows the cap is charging as it should.

Before this, have you checked the motor leads to confirm you have continuity through the motor, and each motor lead to case to confirm no shorts to case?

lg
no neat sig line

 

[mlitt12345]

Update.....I found the problem, 1st pic shows the culprit, the solder failed on a wire to the motor reset button circuit breaker. I soldered it back put it back together turned it on and my air compressor is up and working for about 10 seconds and BOOM!!!!! the start capacitor explodes and I nearly **** my pants. Look at the 2nd and 3rd pic, now I know what the inside of a capacitor looks like. I'm about ready to put this china made air compressor on the curb for someone else to deal with. Any suggestions, is it just bad luck or what? I guess monday I can go to town and buy a new start capacitor and try one last time.

Mike

 

[TireTracks]

Update.....I found the problem, 1st pic shows the culprit, the solder failed on a wire to the motor reset button circuit breaker. I soldered it back put it back together turned it on and my air compressor is up and working for about 10 seconds and BOOM!!!!! the start capacitor explodes and I nearly **** my pants. Look at the 2nd and 3rd pic, now I know what the inside of a capacitor looks like. I'm about ready to put this china made air compressor on the curb for someone else to deal with. Any suggestions, is it just bad luck or what? I guess monday I can go to town and buy a new start capacitor and try one last time.

Mike

WTF.

It's possesed.
I'll give you $1 and a pack of gum.

 

[Zrexxer]

At least now you know the start capacitor is bad...

 

[kams1973]

I'd like to know what caused that to happen. Was the capacitor hanging when you were testing after soldering the wire back in place?

 

[Outlawmws]

it sounds like that motor has more serious issues that just the cap. Was the solder on the loose wire visibly melted? Or was it a cold joint and just failed under vibration? If the latter, try a new cap (And make sire nothing got shorted in the process to cause the cap to pop), but if the former, I'd go buy a replacement motor.

 

[Davefr]

Capacitor quality is terrible these days. (ie the elimination of PCBs and the migration of manufacturing to China).

It's really impacting the HVAC industry.

 

[Outlawmws]

Capacitor quality is terrible these days. (ie the elimination of PCBs and the migration of manufacturing to China).

It's really impacting the HVAC industry.

I don't believe getting the PCB's out had much of an impact. Imported electronic parts from China and other countries without mature technology development on the other hand has impacted a lot of areas...

 

[TireTracks]

Capacitor quality is terrible these days. (ie the elimination of PCBs and the migration of manufacturing to China).

It's really impacting the HVAC industry.

makes me sad, the Cap on my dads table saw is from the 50's is just about dead. Original to the motor, and I bet the chinese replacement wont last 1/10 of that.

 

[larry_g]

A couple of things to look at before you chuck it all. Make sure that your start switch is dropping out, or opening on startup. When the rotor spins up it has a centrifugal mechanism that will move with increased RPM"s and open the switch dropping out the start winding/cap. Make sure that this is working both mechanically and electrically. If the motor is slow in revving up it can also cause the problems you have seen. I would advise you to unbelt the compressor head from the motor once you get thing put back together to confirm that the motor spins up fine and then once your happy with that then put the belt back on and make sure that it gets up to speed without struggling.

lg
no neat sig line

 

[Greatbear]

The start cap should not have blown while the motor was running. By its nature, it is only used to start the motor, once the motor is up to speed, it is switched out of the circuit along with the start winding, and no current will flow through it. What might be happening is the centrifugal switch is not opening once the motor comes up to speed, leaving the starting circuit energized. This draws a lot of power, and the starting circuit is only meant to be used for very short intermittent duty. A cheap Chinese cap, obviously with no safety venting, will be the weak link in the chain.

Look at the white terminal board on the back endbell. The lever and contact is the start switch. It even looks like there might have been a bit of heat happening on the moving contact. With the motor apart the switch should be open. Set the armature into the end bell and see if the actuating disk presses on the switch to close it. You can manually move the weights on the centrifugal actuator to make sure the mechanism is free and that the disk clears the lever of the switch and opens the switch, If not, you've found your trouble. If the switch checks out, try getting a new cap.

 

[Greatbear]

Double post

 

[mlitt12345]

At least now you know the start capacitor is bad...

That is for sure.

I'd like to know what caused that to happen. Was the capacitor hanging when you were testing after soldering the wire back in place?

Yes

it sounds like that motor has more serious issues that just the cap. Was the solder on the loose wire visibly melted? Or was it a cold joint and just failed under vibration? If the latter, try a new cap (And make sire nothing got shorted in the process to cause the cap to pop), but if the former, I'd go buy a replacement motor.

If you look in the 1st pic the brown discoloring on the two black wires use to be a mud dobber nest. The extra weight of that mud clog with the vibration of the air compressor caused it to break at the solder joint.

A couple of things to look at before you chuck it all. Make sure that your start switch is dropping out, or opening on startup. When the rotor spins up it has a centrifugal mechanism that will move with increased RPM"s and open the switch dropping out the start winding/cap. Make sure that this is working both mechanically and electrically. If the motor is slow in revving up it can also cause the problems you have seen. I would advise you to unbelt the compressor head from the motor once you get thing put back together to confirm that the motor spins up fine and then once your happy with that then put the belt back on and make sure that it gets up to speed without struggling.

lg
no neat sig line

So in the 1st pic the brass contact with the points should be open with the end bell off and when you install the end bell back the points should close.

The start cap should not have blown while the motor was running. By its nature, it is only used to start the motor, once the motor is up to speed, it is switched out of the circuit along with the start winding, and no current will flow through it. What might be happening is the centrifugal switch is not opening once the motor comes up to speed, leaving the starting circuit energized. This draws a lot of power, and the starting circuit is only meant to be used for very short intermittent duty. A cheap Chinese cap, obviously with no safety venting, will be the weak link in the chain.

Look at the white terminal board on the back endbell. The lever and contact is the start switch. It even looks like there might have been a bit of heat happening on the moving contact. With the motor apart the switch should be open. Set the armature into the end bell and see if the actuating disk presses on the switch to close it. You can manually move the weights on the centrifugal actuator to make sure the mechanism is free and that the disk clears the lever of the switch and opens the switch, If not, you've found your trouble. If the switch checks out, try getting a new cap.

Will check the white terminal board start switch tomorrow. Thanks for every ones input.

Mike

 

[mlitt12345]

Got it going......the problem was when I took off the end bell the spring came out of position in the white terminal block causing the start switch to not drop out like it was suppose to do. Fixed that and replaced the start capacitor and happy to have air again. Thanks for all of your help.

Mike

 

[kams1973]

Thanks for the update and good job.