Snap On AC 10120 H 10hp compressor slows down at 145 psi, cut off is 175 or 180 psi

by Phil Schmit
(Rockwell City, Iowa USA)

I have a Snap On AC 10120 H 10hp dual cylinder air compressor.

The motor burned out and I replaced it with a refurbished 10 hp motor withe the correct RPM rating of 1725.

Now, when it gets to 145 - 150 psi the compressor "loads up(?)" and almost stops. The pressure switch leaks the whole time the compressor is running normally.

When it slows and labors I immediately shut it off. The pressure switch stops leaking when not running.

What I've done so far is replace the valves in the larger head, one was cracked, cleaned the valves in the smaller head. Cleaned the check valve.

_______________
Bill says...

Check the unloader valve page and the check valve page linked from the site map. If, and when, you have fixed your unloader valve and / or check valve problem, please write back in as a comment here and give me an update.

Cheers,

Bill