Here's a tip from an experience of mine - some shops don't know that on these trucks, the AC controller in the dash will shut down the system entirely if the compressor tries to kick on 10 times with low or no charge. This can be problematic when attempting to charge the system because you need the A/C on to do it! You can tell if it shutdown by a blinking A/C light on the controller when A/C is turned on.
In order to reset the system, either the battery or controller has to be disconnected. This will most likely need to be done several times during the charging procedure, unless the tech is smart and knows to turn off the A/C button every now and then to prevent a shutdown.
A popular mod which I did on my truck is to remove 1 wire from the A/C controller wiring harness - REMOVE, not cut, from the terminal. This will allow the compressor to cycle forever regardless of system pressure.
I would also test the 3 pressure switches, located on the condenser, compressor, and accumulator - upon removing the electrical connector from a switch at a time the compressor should not run at all.
Best of wishes!
In order to reset the system, either the battery or controller has to be disconnected. This will most likely need to be done several times during the charging procedure, unless the tech is smart and knows to turn off the A/C button every now and then to prevent a shutdown.
A popular mod which I did on my truck is to remove 1 wire from the A/C controller wiring harness - REMOVE, not cut, from the terminal. This will allow the compressor to cycle forever regardless of system pressure.
I would also test the 3 pressure switches, located on the condenser, compressor, and accumulator - upon removing the electrical connector from a switch at a time the compressor should not run at all.
Best of wishes!
