Compressor completely drains from the switch box

by Chris

Central Pneumatic Model 94667 pressure switch

Central Pneumatic Model 94667 pressure switch

I had my compressor run from nearly no pressure in the tank and I noticed that after the tank was full and motor stopped, there was a heavy leak that was near the tubing that goes to the on/off box.


The air wasn't coming from the fitting of the tube, rather near the bottom of the small plate the tube screws into.

I have no idea what this tube is other than you can see a contact point for when you toggle the on/off lever. I tried looking in the manual and it provides no help at all! See attached picture for the area I am talking about.
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First visit the tank check valve and unloader valve pages on this site to understand what they are and how they work together.

Knowind that will help you understand what is likely happening on your 94667 air compressor, Chris.

Bill

Comments for Compressor completely drains from the switch box

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Nov 14, 2014
Thanks!
by: Lee

I too had this same problem and now is fixed!! Thanks guys & Bill keep up the great work.

Jun 12, 2014
I had this issue but fixed it
by: Tom

I found this site after a simple Googling of "compressor lets out air after filling" and found the page about the unloader valve. If you look at the manual, it's part 18A. I figured mine was shot. Before removing it, I saw there was a 19mm nut on the end of it. I pulled that off, the rubber cup came flying out so be careful not to lose it. There was actually a piece of gasket material inside the valve, causing it to leak constantly (likely from the head gasket not being cut properly @ the factory). I pulled that out, put the rubber cup back in, and put the nut and spring assembly back on. Bingo, problem solved! Considering I bought this thing in 2011, it's used about once a week for 2 cycles, and I only paid $115 for it with tax / after the coupon, I would say I've gotten more than my money's worth from this compressor.
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Yeah, Tom, we musn't lose sight of the fact that a $100 compressor that's still working after a few years really didn't cost all that much per year.

That and, for sure, make sure you dump all the air from a compressor and power down before you open up any air fitting on it.

Bill

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