Alpha Carette Repair Information

I have a Carette air compressor with Joe Brancato Alpha filter and I am having problems. The compressor has about 20 hours on it.

It appears to me that the compressor is putting out less volume of air per unit time then it did originally. Here is what I have done.

Compressor is off.

Connected a 97 cu ft air tank at 3500 psi.

Tank valve closed.

Turn compressor on.

Compressor fills the filter and hose. Pressure will increase to 4500 psi and compressor shuts off (just like it should).

I bleed off all air from filter and hose.

Tank valve still closed. I start compressor and increase pressure to about 3000 psi.

I open tank valve slowly and equalize pressure between hose and tank.

Pressure in tank begins to increase very slowly. From 3500 to 3800 psi in 50 minutes. The tank used to fill from 3500 to 4500 in about an hour.

I have soap tested all joints and there are no leaks.

The compressor is cool to the touch throughout the cycle.

Does anyone have any ideas on how I should proceed?
 
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Th first two things I would suspect are the pressure valves need cleaning or replacement or the high pressure rings need replacement. The high pressure side appears to be the culprit. I am no expert but have had the same symptoms and one or both of those fixes were recommended to me by the MFG. When replacing the rings it took three starts for the pressure to raise. New rings needed to seat and I had not anticipated that. So It went to 1000psi then 2000 psi then finally up tp max. 

The pressure valves on the hi-pressure side get very dirty and can wear/ scar the valve seat preventing solid seal. In my case the problems were cumulative with both causing drops in psi output. Again no expert here so please throw no stones. Good Luck
 
Well, I was able to get my Carette fixed. I came up with some useful information that I want to share. First off, thank you SoCalOldMan. In your post above you hit the nail on the head. I was able to find this great video on how to disassemble the HP side of the compressor and what to do. I'm no expert, but I was able to follow the video easily. Also in the course of messing around with the compressor before I found the video, I blew an o-ring in the Alpha filter PMV. I was able to get a drawing of the PMV with parts list from Joe Brancato (on a Saturday) that allowed me to fix the PMV. Thank you Joe for the drawing. I also want to thank Humdinger for your valuable consultation. Here are some things that I learned:

Make sure there are no leaks. The smallest leak can affect the ability of the compressor to fill a 4500 psi tank.

There is a dead head plug that came with the compressor. If you put that in the end of the compressor discharge hose and turn the compressor on, in my case the pressure rose from 0 psi to 4500 psi and shut off in 90 seconds (after I followed the video). Before the video, it took around 20 minutes.

If I think of anything else, I will post later. Here is the video and PMV drawing. I am feeling much better about my Carette compressor. I was beginning to wonder if the trash man would take it, if I left it curbside.

https://www.youtube.com/watch?v=Q6pxOBwMISg

1546863229_404044115c33427d5240b1.19393144_Carette PMV Drawing and Parts List.png