OK guys, My first post here. I have searched for an answer to my AC issues on other threads and haven't seemed to find anything. I have an 06 2500. The AC compressor will run a couple of seconds and cycle off then on. I have taken it to a couple of shops and they have tested the system and verified it has proper freon levels. When plugged into the computer (at the repair shop) the tech sees where it is showing that it the compressor is losing communication with the ECM and he has no idea what is causing this. He can reflash the computer and the AC will work for maybe 20 minutes and blow cold then you can cut off the truck and let it set for 10 minutes, try it again and the compressor will go back to cycling every few seconds. It's hot here in Alabama so I need to get this thing to work.. Any help would be appreciated!

 

Did you mean the computer was losing communication with the ECM???
There was NO communication between the compressor and the ECM.

ECM reads the A/C Clutch request (from the control head) on the data bus and the AC pressure transducer signal from the transducer and determine when to cycle on/off the compressor clutch.

ECM communicates with the control head.

 

Don't know if this applies to your year specific truck but there has been a problem with wires rubbing and chafing against the intercooler piping below the compressor...take a look and see if there is a sensor on the AC line there with the wires against the metal pipes....