# Coleman air compressor issues



## iamrfixit (Jan 30, 2011)

Part number 9 in your parts list. This pressure switch controls the *TANK* pressure, the regulator only controls the *HOSE* pressure. The pressure switch has a range of approximately 95-125 psi. The switch will not run the compressor motor until the pressure drops below the low end set point.

If you have less than 90 psi of tank pressure and the compressor is not running the pressure switch may be bad, sometimes the contacts in the switch arc and become damaged enough they won't make contact when the switch closes. It could also be several other things. 

Does the unit have an ON/OFF switch, is it in the right position? You could also have a blown breaker, try a different receptacle? You could have a loose or broken wire, the motor may have a reset that is popped or the motor may have failed. 

To properly diagnose it you would need to use an electrical tester to find out if you have power through the switch, to the pressure switch, and to the motor.


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## Richo (Dec 6, 2007)

It's none of the obvious things like the switch off, bad receptacle, breaker, etc.

About a year ago when it would not kick in after it went under 100 psi, I opened it up and the switch was not engaging (not the on/off switch but the switch shown here)










That seems to be working OK right now but the real issue is the reading on the 2 gauges. I released every last bit of air from the tank using the drain valve on the bottom, and the gauges still read 60 psi (output) and 85 psi (tank).

I have a hard time believing that both gauges are faulty so what could it possibly be? Thanks


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## Thurman (Feb 9, 2009)

You have a problem believing that both gauges could be bad? I don't, and I've worked on compressed air systems for over 30 years. Mass produced air compressors for the consumer market are built with the lowest cost (in other words--cheap) gauges. By design, Bourdan tube with rack/pinion gears, is a poor system for frequent pressure changes. Drain the pressure from your unit with the power OFF. Then start the unit and let it cut off (the cut-out point). Release air from the unit _slowly_ by any means until the unit starts back up (cut-in pressure). This tells you you pressure switch is working or not. IF it doesn't work like this=bad pressure switch. IF it works go buy two new gauges which read at least 50% more than the rated pressure(s). If this unit is rated at 120#, then buy 200# gauges. If you pay up for "liquid filled" gauges they will last forever.


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## Richo (Dec 6, 2007)

> Drain the pressure from your unit with the power OFF. Then start the unit and let it cut off (the cut-out point). Release air from the unit _slowly_ by any means until the unit starts back up (cut-in pressure).


I actually did this earlier today and it started back up when the pressure dropped a few pounds.

I guess I will look into replacing the gauges and hope that fixes it. Just thought it was odd that both would go bad at the same time.

Thanks for the info


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## Richo (Dec 6, 2007)

Obviously is a bad gauge. I removed it from the compressor and it reads 80 psi while holding it in my hand.

Can't believe those gauges cost $27 a piece to replace. Buying 2 of them is almost half the cost of a new air compressor.


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## Maintenance 6 (Feb 26, 2008)

Richo said:


> Obviously is a bad gauge. I removed it from the compressor and it reads 80 psi while holding it in my hand.
> 
> Can't believe those gauges cost $27 a piece to replace. Buying 2 of them is almost half the cost of a new air compressor.


Not if you buy a really good compressor.


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