Comp Pressure Switch Help

[Rstark18]

Hey guys. I need to adjust the pressure switch on my compressor. It cuts in at around 80 and out at 120. I want it to cut in at 100 and out at 130. I have what looks like a Condor MDR21 but it doesn't have the 3rd adjustment screw that would be the differential adjuster. See picks. Which adjustment screw does what.

 

[kams1973]

Usually there is a sticker under the pressure switch cover w/ illustrations.

 

[The Cobbler]

failing what previous poster said, try to back off 1 nut 2 or 3 turns & see what it does to your pressure . repeat with other nut .

 

[skulldrinker]

you can buy a 95-125 psi switch on Amazon for $20. If you can't make yours work.

 

[Rstark18]

The diagram is only electrical.
I was just hoping someone would have some experience with this style switch to save me the time of experimenting without knowing if one is a differential or a cutout.

 

[comedyman809]

trial and error

 

[skruft]

I agree, try it, carefully. I think one must be cut-in, the other cut-out.

 

[Rstark18]

I'm very confused. Both affect cutout and both seem to affect differential WTF.
I kept adjusting the top but until I got the cutout pressure that I wanted. Then I increased the bottom but for the cut in but it also I increased cutout.

 

[The Cobbler]

I have a portable compressor , replaced the crapped out switch with a Chinese knock off. it had no differential setting. 2 adjustments, 1 didn't seem to do anything, the other only raised or lowered the cut off pressure. I wanted to boost the cut in from 80 to at least 95( 80 is too low for running 2 air staplers when doing underlay) . ended up tossing it & replacing it with a switch that I could control. sorry, should have mentioned that in my original post.

 

[Rstark18]

Well both springs seem to do exactly the same thing.
Top nut one turn clockwise is a 4psi increase in both cut in AND cut out.
Bottom nut one turn counterclockwise is a 4psi decrease in both cut in AND cut out.

 

[Fixnair]

I wouldn't try messing with the differential. Those cheap pressure switches aren't really designed for that. It will only leave you frustrated.

 

[Rstark18]

I wouldn't try messing with the differential. Those cheap pressure switches aren't really designed for that. It will only leave you frustrated.

Good advice I guess. I'm leaving it with the last adjustment being cut in 88 and out 138. I wanted it close to 100/130 which is what it was for years but at some point in the last year shifted.