Compressor doesnt shut down (video)

[RVJimD]

Guys,

I posted a video of my quincy compressor. I have been having trouble with it NOT shutting down consistently. In the video you can hear it running and the unloader valve opens and bleeds of air, then closes and the compressor continues to run. It never does make too much pressure. In fact it has never developed more than about 100psi. It occasionally seems to work just fine, and usually if i let it run it will eventually trip the pressure cutoff and shut down. I don't understand these contraptions so im not sure where to look. The diaphragm of the unloader is okay.

Hint appreciated!

 

[kd4gij]

It is your pressure cutoff switch. It should look something like this . The electric will go to this then the motor.

 

[kev74]

Either your off switch is set to a lower pressure than the relief valve, or the switch isn't operating properly (more likely).

My compressor did something similar a few years back. I was able to clean out the accumulated dust and debris from the switch and that brought it back to working order. I don't remember if I used compressed air or electrical contact cleaner or both.

 

[RVJimD]

Ya, that is what it looks like. The motor is 220v, if i end up replacing the switch, i suppose there are different styles/types and i will need the same as it has on it huh?

 

[kd4gij]

You need one for 220v and what ever pressure that your tank is rated at. If the tank is rated at 120psi the switch needs to cut off at that point.

 

[dlane]

Most are adjustable , ied mess with it and make it work if possible , carful with live electricity.

 

[magicniner]

I had a similar issue with a 1940s compressor, the contact surfaces had eroded away and the carrier metal was welding shut, a local industrial motor rewind company which I use supplied me with a handful of replacement silver contact buttons, it's been good ever since.

 

[Hukshawn]

The cut off pressure for the switch has risen higher than the blow off pressure for the relief valve. Either because one or the other is worn out or needs adjustment.

 

[talvare]

That appears to be an oil pressure type unloader on the end of the crankshaft. When oil pressure is low (as at start-up) the unloader valve on top of the cylinder will relieve air pressure until the oil pressure is up to operating level. It's possible that the compressor isn't making adequate oil pressure or more likely that the hydraulic unloader valve needs to be removed and cleaned/rebuilt. Some of those hydraulic unloaders have very small fiber type filters in them that get clogged up. First make sure the oil level is where it is suppose to be. Then I would either install an oil pressure gauge to verify running oil pressure or just remove and rebuild the hydraulic valve.

Ted

 

[woodchucker]

Either your off switch is set to a lower pressure than the relief valve, or the switch isn't operating properly (more likely).

My compressor did something similar a few years back. I was able to clean out the accumulated dust and debris from the switch and that brought it back to working order. I don't remember if I used compressed air or electrical contact cleaner or both.

I think he got that wrong. The switch is set for a higher pressure than the relief valve.
Usually the relief valve only fires off once the unit shuts.
A just adjust the screw, B you may need to clean out the little pin that pushes out from the tube that indicates the pressure is at max.. I had to do both to mine. It just got gunked up, and after I cleaned it, I needed to reset things. Pretty minor stuff.