Here's my tale of woe, not yet resolved.
www.traverseforum.com
Most common causes: Bad air flow actuators, leaks in the refrigerant lines going back to the rear AC, an AC line in the engine compartment that rubs on something nearby.

Passenger side not cooling, actuators OK
So if you're following me, I just replied to Megan this morningregarding her AC issue. I explained to her how the compressor supplies both front and rear evaporators and a quick explanation of the actuators. I mentioned that I was having an intermittent issue with my actuators, but hadn't...
Most common causes: Bad air flow actuators, leaks in the refrigerant lines going back to the rear AC, an AC line in the engine compartment that rubs on something nearby.