Compressor troubleshooting - Rolair JC10

So my Rolair has been acting funny for a while. I don't know much of anything about compressors, so I don't know if this is an easy fix or a big problem. I'm hoping my description of the problem will trigger an obvious answer.

Occasionally the compressor will fail to recharge - the pressure will drop past the threshold and the compressor will be silent, but a burning rubber type of smell will come from it. A few flips of the on/off switch will usually start it up again (with no smell). During those flips, either nothing happens or it will try to start but fail to get going. Usually a few flips of the on/off switch get it going. This problem almost always occurs at recharge, or if the compressor is started up when the tank is partially full. It hasn't occurred when starting the compressor on an empty tank.

Any ideas? I'm right in the middle of a trim project and I need my nailers. :(

Victor, it is possibly the non return valve. When this is leaking the compressor is trying to start fully loaded. Cheers

Two possible problems with compressors, but I'm not familiar with your compressor.

There is a pressure bleeder that removes air from the line between the compressor head and a check valve at the inlet to the tank. This is usually a small line that connects to a bleeder valve in the pressure switch that is activated when the pressure switch is off. If it doesn't remove the pressure in the line and compressor head, the compressor is trying to start under load. It needs to start with little or no load during the first couple of revolutions. You should hear a hiss for a few seconds after the compressor shuts off, if it's working properly.

There is a starting capacitor in a bump on the side of the motor that is switched in and out by a centrifugal switch in the no shaft end of the motor.
Either the capacitor is bad or the centrifugal switch is not operating. The capacitor is easy to change. You can get a replacement at any motor service center, Grainger, McMaster Carr, Amazon, etc. Be sure to buy one with the exact electrical specifications and physical size. The switch will require dis-assembly of the motor. What usually needs attention is the centrifugal fly weight assembly on the motor shaft that actuates this switch. The weights swing out from the motor shaft as the motor speed increases and back as the speed decreases. They move a plastic collar on the motor shaft that actuates the switch in the end cover of the motor. Usually the area on the motor shaft where this plastic collar slides gets dirty or rusty, preventing the collar from moving sometimes. Clean and polish this area of the motor shaft and then apply a very thin layer of synthetic grease. Then wipe off all of the grease. What is left in the pores of the metal is sufficient to lubricate the collar. If you leave extra, it will fly off and create problems. You just want to keep the collar sliding easily.

Check the bleeder first, but the smell may be coming from the starting capacitor. It has a pressure relief and when it vents you will smell a strange odor, and sometimes liquid will spray out. It's a sure indication that it's bad when it does this.


Charley

I own a JC10 and had what I believe is the same problem. The issue for me was a bit of debris keeping a check valve partially open. This caused the tank not to fill and the motor ran longer than it should. The motor is not rated for continuous duty and left a smell like you mention. I contacted rolair service and they instructed me to so the following:

1. unplug the compressor
2. drain all the air out of the compressor
3. carefully unscrew the check valve cover. Be careful there is a small spring inside.
4. clean out any small debris in the valve
5. reassemble the check valve making sure the spring is in place

After I completed those steps the compressor worked as before. It's nice and quiet as before.

Hope that helps.

I circled the check valve in a photo of my compressor. It's not incredibly obvious where it is.

Attachment 341388

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Originally Posted by Victor Robinson

So my Rolair has been acting funny for a while. I don't know much of anything about compressors, so I don't know if this is an easy fix or a big problem. I'm hoping my description of the problem will trigger an obvious answer.

Occasionally the compressor will fail to recharge - the pressure will drop past the threshold and the compressor will be silent, but a burning rubber type of smell will come from it. A few flips of the on/off switch will usually start it up again (with no smell). During those flips, either nothing happens or it will try to start but fail to get going. Usually a few flips of the on/off switch get it going. This problem almost always occurs at recharge, or if the compressor is started up when the tank is partially full. It hasn't occurred when starting the compressor on an empty tank.

Any ideas? I'm right in the middle of a trim project and I need my nailers. :(

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Have you checked w/ the Rol-Air people? If it's a well known, documented issue, they may have a fix and tell you how to fix it.
Worth a phone call or e-mail I imagine. Good luck.
Mac

Thank you very much all - will try the easy fix Chris mentioned and then probably contact Rolair before embarking on more involved operations. Charley that was quite an education on compressors and I really appreciate it.

Mac - will definitely get in touch w/ Rolair...just wanted to see if anyone had the same issue before going down the tech support path, which as you know is sometimes easy and quick and great but also often time-consuming and disappointing.