Ok I have never seen this before...I bought the truck with two issues : no ac and bad drivers side qindow motor assembly. Window was fixed the day i got the truck...driving home i popped the mil...had to replace the knock sensors, idle colntrol valve, and canister purge solenoid. This week end I set off to fix the a/c. ( The old compressor was leaking from front seal) replaced the compressor,dryer,and orfice tube. Flushed the system, replaced every seal in the system. Pulled a vacuum, and charged the system this is where it gets weird. ( at idle gauges are reading 34lbs low side 240lbs high) Everything is fine at idle..ac blows cold 60f at vent as soon as i rev engine up the ac clutch lets go...it wont re engage until the idle comes back down...i bypassed the low pressure switch and it holds all the way to 5k rpm. So i went and got a new clutch cycling switch..still kicks out with new switch. Any ideas wth could be causing this?

 

how did you charge the system?


model year, engine ??

 

Truck is a 2000 model 1500 Silverado 5.3L xcab..cai...magnaflow cat back...with tuner...
Charging: after holding vac for 30 mins introduced freon thru gauges little at a time..open for few seconds...closed for 30 seconds until gauges read 36-42 on low side 230-250 on high side...ambient remp was still almost 90 degrees with 90 percent humidity. Truck was at idle throughout...buddy recomended idling truck up and spraying condenser with water while the gauges are hooked up to get a more accurate reading from the gauges...the only thing i dont have is a scale to weigh the cans...ive never had to do this before...done prolly 25ish ac jobs on my vehicles before

 

what are the pressures before the compressor disengages? First things first I'd recommend finding some scales or someone with a machine since you really don't know how much refrigerant you put in the system.

 

ditto

the charge method is not accurate. the charge level is "prolly" low...when the compressor is pumping fast, it creates a low pressure that trips the low psi switch. that is why is works properly when you jumper the switch. have the system accurately charged

 

I have a Qestoin I just bought a 2000 Z71 and the A/C was working fine and now it's blowing hot air so I did what any one else would do and bought a can of a/c recharge and hooked it up and it said it was running fine the compressor was working fine, and then gage showed that I didn't need to pump any in it, or I would over fill it. What should I do?

 

Make sure your fan clutch is working properly.