I have a 2004 Silverado 2500HD and the air conditioning is acting up. I will be driving along and all of a sudden the AC will start blowing out HOT air on the driver's side only. It's got the dual zones, and the passenger side stays blowing cold. If I turn off the engine and then start it right back up it goes back to blowing cold on both sides.

Anyone had this happen before or know what may cause it?

Failing blend door actuator.

This more or less applies to your truck, too:

http://www.sparkys-answers.com/2009/09/2004-chevrolet-tahoe-blows-hot-air.html

Also, pay careful attention in the comments about the resetting procedure for the AC system. If you don't do it as described, it may seem like the fix didn't work.

Exactly what I was looking for. Thanks for the help.