I sometimes get an issue when I,turn the heat up to 90 I get hot air on my passenger side but reg temp air on driver side, same when on deffrosters. I have to turn the car or and then start and it evens out. Not having issue much with the ac but has happened once. I had a guy say it was the left air mix servo motor but I can't find that part on a hummer but do see a part called an actuator that has a left and right. Anyone have this prob and if so help me identify the issue and fix.