I've done a search but everyone seems to be having the opposite problem i'm having.
Today at lunch i went out, 98 degrees a/c worked fine, cooling normally. After work I get in the truck to go home (101 degrees) and when I start it up the vents are blowing warm air. I checked the switches and everything is correct, the a/c is on full blast, haven't touched anything since I hopped in at lunch. Then I noticed that the passenger vents are both still blowing cold, I slid the driver side temp control to hot and it got even hotter and seemed to stay really hot even when I moved it back to cool. Then I turned the blower completely off and back on and it seems to be back to just slightly warm air and passenger side is still cold.
Everything I found in the search seemed to be the opposite with the passenger side getting warmer so if anyone else has had the drivers side get warm let me know what you found out.
Thanks.

 

Mine was opposite. Pass warm driver cold. But a can of freon fixed it. Might try that anyway just to see.