The AC system was not blowing cold air so I checked to see if the compressor was coming on. It was not. I got a bottle of R-134A, the one with the hose, fitting, and guage. The gauge said that the pressure was around 110 psi, but the compressor was not running so this was still a static pressure. As a test, I jumped the cycle switch (pressure switch) and the compressor turned on. I got in the truck and the AC was blowing cold. So, I assumed, which is probably not the best idea, that the switch was bad. I went and paid 100 bucks to have the system evacuated and a new switch installed. Now, the compressor runs for 5 seconds, stops for 10. It continues this cycle over and over. This truck is a 2003 Silverado 2500 with about 40,000 miles on it. Does anybody have any suggestions? What happens if a system is overfilled with refrigerant? Is there a switch that will shut the compressor off prematurely?

 

yeah dude, pressure switch which is in the reciever dryer. with the system low or high it'll cycle on and off..

 

I just had my 2003 Chevy HD2500 4x4 Duramax/Allison (with approximately 75,000 miles) in the shop last week for the same problem. I purchased the same type of R134A and it showed that I had too high of pressure. I took it in to the dealership under extended warranty and they replaced the AC Compressor. This did not provide any results - AC blew 77 degrees at the Vent on a 96 degree day. My wifes suburban blew 54 degrees at the same time, so I knew that the problem wasn't fixed. I took the truck back into dealership the next day and the replaced the Accumulator. Now my truck is blowing colder than the ever. 46 degrees on a 96 degree day.