I just started having AC issues with my 2012 Sierra.
The symptom is blowing warm air on all vents.
Here is what I have checked so far.
Compressor clutch appears to be engaging and cycling
I checked all fuses and relay, no issues.
The only thing I have notices is the short line that comes from the firewall is very cold / frosted. This line is approximately 12 inches long.
The coldness stops when it hits the first line connector.
As far as AC compressor - At first start the clutch engages, runs continually, Short AC line frosts up. After idling for several minutes the AC line thaws out some but is still cool and the compressor clutch starts cycling on and off every 5 seconds.
Any suggestions on what to look at next would be appreciated.
