why does ac cycle ? & fuel press ques ?

1) what causes the compressor to constantly cycle on and off ?
about every 5 seconds it cycles for 1 second ? i unplugged it for now

2) it's been a while since i had a hood mounted fp guage. i don't remember where it should travel around. i am searching for a problem thats why i ask

at idle it's about 34psi
as soon as you give any gas, it rises around 38-40 psi
wot 42 psi
letting off w/ the r's up high enuff to have some engine braking effect it drops down to 32 psi

pretty sure this is normal, but under the littlest load 40 psi seems a bit phat ? maybe i'm wrong. i spray so i'd rather be phat than lean
 
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Assuming that there is not a malfuction somewhere in the system, the AC compressor cycles off and on when the system is on. Bear in mind that the AC runs when the HVAC controls are set to "defrost" as well as AC.
 
If your A/C is constantly cycling, your A/C Clutch cycle switch could be bad. When my A/C was constantly cycling, that turned out to be the culprit. The A/C clutch cycle switch is the plastic switch on top of your A/C Accumulator.
 
You might want to take it in to have it looked at. It will be much cheaper than throwing parts at it. What you described could be several different things.

With the A/C: Does the RPM drop more than 100rpm when it turns on? If so, it could be a slow or dirty IAC. Have you checked your pressures. What do they read? What do they do when it cuts on? Low freon, low rpm, a clogged system, overcharged and or bad switches will cause the A/C to cut off.

Fuel pressures are controlled by the regulator which adjusts fuel pressure according to engine vacuum. Those readings are normal.