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Just picked up my jc10 compressor from ups and noticed a small compression nut on the pressure switch that is loose. It is located on the side of the switch box, small pipe comes up and has a compression nut on top. What is it for?
 

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Had mine for a few years it has the same fitting, I believe it is the vent for the compressor head. The head has to be vented on shut down so the motor does not have to start against pressure.

Tom
 

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Had mine for a few years it has the same fitting, I believe it is the vent for the compressor head. The head has to be vented on shut down so the motor does not have to start against pressure.

Tom
Thanks Tom. I'm loving this thing. I've drained it down a few times just to listen to it run... :laughing:

I told my wife, I knew I was going to be impressed at how quiet it was, but I was more impressed than I thought.

But to the issue at hand, would that make it where it draws less amps on startup since it's not under pressure?
 

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The motor may not have enough initial torque to over come the head pressure. The unit may not even start, just hum then shut down on thermal.

If you have ever had a compressor that leaks out of the swith when the unit reaches set pressure then shuts down it is most commonly the unloader leaking.

Tom
 

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There is nothing attached to that fitting on mine either. I couldn't tell where the pressure release came from after full pressure but it didn't seem that it was there.

TBF, you talking about that little thing with a red light on it in the middle?
 

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Wait, what? My jc10 uses an electronic unloader. That fitting is unused on mine.
As I stated "I believe it is the vent for the unloader". I do know that the unload is an electrical function on the Jc10, I thought it dumped through the fitting. I'll check it tomorrow.

Tom
 

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if you are talking about part 52 on this diagram http://www.mastertoolrepair.com/images/JC10_rolair_air_compressor_parts.gif
then it's the vent for the unloader solenoid. When solenoid denergizes it will vent the small amount of air that was holding the unloader piston closed out that fitting. The majority of the air vented is going somewhere else.
On High Pressure compressors that vented air may be wet and oily so in the interest of cleanliness a tube may be attached and run to the condensate collection tank.
To satisfy your curiosity switch the compressor off with your finger blocking that fitting off. You should get a small puff.
 

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48 is the pressure switch, the diagram does show the fitting in question mounted to it.

I went and looked at mine, It is the unloader vent, tilt the compressor and you will see a small arm that acts against the piston in the fitting. Bleed the compressor so it starts, you will notice the arm moves away from the unloader, when the unit shuts off the arm acts against the piston and the head unloads.

Tom
 

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Looking at that part it appears to be a combined pressure switch and unloader valve. The tube and nut do not do anything on this compressor. Just a Schroder valve in there from what I can see.
If you had a two stage compressor you could unload the first stage by connecting it into thay Tube fitting. with a single stage compressor a second unloader is not needed.
 

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I think it's actually the tube with the nut on part 48. If I remember correctly, not in the shop right now.
That is the mechanical valve for an unloader. It is unused on the jc10 due to the electronic one (part 52). Part 52 does not connect to it. Your compressor is as it should be.
 

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TBFGhost said:
That is the mechanical valve for an unloader. It is unused on the jc10 due to the electronic one (part 52). Part 52 does not connect to it. Your compressor is as it should be.
And one day I'll read and understand air compressors too. :)
 
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