2003 Silverado AC issues

[nickbartels]

I am having issues with the AC on my truck, and it just up and quit on me today. For a couple years now the AC has been cycling on/off. Sometimes it wouldn't come back on until I thumped the low pressure cycle switch on the accumulator. I replaced the switch with a new one from Chevy. Still cycled on/off but at least I didn't need to thump it anymore.

Recently a family friend threw a set of gauges(I have since purchased my own set of yellow jacket gauges) on the it to see if we could determine the issue or at least see if it was low. I believe it read 45psi (low side) and 225psi (high side). He checked with his HVAC buddy and it was decided it was low. We added a can of freon and it now read 60/275. It still cycled on/off. However after adding the can, the temp at the center vent was 45-55 degrees(depending on the day and if I was at idle or cruising down the road).

Since it was still cycling, I put my gauges on to start the troubleshooting process, on a 95 degree day in the sun. At idle, I had 60psi low, 300psi high, center vent was 50 degrees. I held it at 2000RPM and it started cycling. In just about 4 seconds it would go from 60psi to 30psi on the low side and cycle off. The high side didn't really jump up or down when this happened. It would start to equalize the pressure(another 4 seconds) and would cycle on when the low side got to 70psi. Then the process started all over again. Returning to idle would stabilize the pressures(at least until it went above idle again. Going down the interstate, I can tell it was still cycling on/off. I could feel the temp of the air change coming out of the vents, and the timing was about the same as I experienced sitting in the driveway with the gauges connected.

Well...Today it just stopped altogether...I thumped the low pressure switch, nothing. I jumpered the low pressure switch and it came back to life, kind of. Low side reads 65psi and high side roughly 300-325psi. The temp at the center vent is about 65-70 at idle and about 60 at 1500-2000RPM. Currently 95 degrees outside.

ANY help would be appreciated. I fear I will be replacing some expenses parts, but hey, its just money right?

Thanks in advance!
Nick

[usmcchevy]

Anyone?

[truckdude239]

45 psi and 225 on high side is a good reading 60-275 is high way high sounds more like a problem maybe with the controller. i'd have all the frezon pulled out it it recharged to factory specs. i chared one the other day with my machine it it was runnign 45 on low and 220 on high with a vent temp of 35 degrees