I have a 2003 Hummer H2, the A/C is no longer working. Compressor, condenser, receiver/ dryer were replaced a few years ago and recently evac and recharged the system. I have ran the diag on these and I have checked the A/C low pressure switch; all readings good. I also have access to a Snap-On Asus Scan tool. I am able to turn the A/C on with the scan tool and it works great. I can hear it turn on and feel the temp change, however if I try to turn in on using the A/C button on the HVAC control module, nothing happens. All other functions on the control module work. Do I replace the control module or could it be something else I am missing.

 

This is a very complex unit. I just read through the troubleshooting steps and it was extremely lengthy. I am just guessing but I think the good news is it worked through using the tool. So I would start simple and start with loose connections and the switch. I will PM you the steps for the basics with the DTC in the morning.

T