99 Peterbilt A/c cycling on and off

Is there a sight glass in the receiver drier (filter can)? Did you buy brand name parts such as Sanden compressor and match them to the old ones before installing? There is a lot of cheap imitation junk out there. Did you use cans or a cylinder/tank to charge? Did you bleed the air out of the hose? Air in the system can cause high discharge pressures. Orifice tube goes with an accumulator system while expansion valve goes with receiver drier.

Static pressure should be in the high nineties, about 97 psig. Low static pressure could indicate an undercharge. I would have someone recover the refrigerant now in there and charge by weight and see where things end up.

 

How long does it take for your high side pressure to turn your fan on? And does your high side pressure drop when the fan comes on?

Your low side at 20 could very well be kicking out your low pressure switch, and if it takes a bit for the fan to come on from high side pressure, it's likely low.

And what is your ambient air temp?

 

I'd probably add some freon.

 

You could turn your manual fan switch on, and usually high side will be 175'ish, 35'ish low side, when full.

Obviously that's a rough guide, and subjective to other conditions.

Clean engine bay, BTW. Nice

 

Post #6 - "this is pressure with truck off" Your gauges read about 52psig. Chart shows high 90's. Your barely over half of what the reading should be. You said outside temp was 87 F. Look at pressure on chart.

In post #13 you state "The static pressure is right." How is the static pressure (truck not running) right????