GMC Repair: 2005 GMC Yukon Dual Climate Control, gmc yukon xl, gmc yukon xl denali

Question
I recently purchased a 2005 GMC Yukon XL Denali, with 44,000 miles.  While on the test drive with the AC on, The driver's side began blowing extremely hot air.  The passenger side and rear air continued to blow cold.  All controls were set at 60 degrees.  I tried turning the AC off and back on (problem persisted), but when you turn the engine off and restart it, the issue was corrected.  The dealer told us an actuator or regulator was bad and that they replaced it so we subsequently brought the vehicle.  Well, we've had it for around 30 days, and it has done it two more times since.  I had it back to the dealer two days ago and was told I would have to stop in when it is acting up for them to diagnose the issue.  The problem is that I live over an hour away from the dealer, and when you shut the vehicle off, the issue corrects itself upon being restarted.  It's a real pain (let alone unsafe) to keep pulling to the side of country roads to shut off and restart you vehicle to get the AC working properly again.  I spoke to a man who told me his 03 Suburban was doing the same thing and the computer had to be replaced to correct it.  I also found a post on another website refering to the same issue and it suggested disconnecting the AC control unit wiring harness and "replacing all", but I am unsure what "all" needs to be replaced.  Can you offer any advice on this issue? Thanks in advance!

Answer
i would definately see if they can reprogram the climate control acutators, if they replaced one but did not program it, you could still have an issue, if that does not correct it then it could in fact be the module, which is the control head in the dash