I have a 2001 monte carlo, the drivers side temp control only works sometimes. I changed the controls ... same thing though.

 

Is it one of those things where if you bang on the dash it works? I am just trying to see if its just a loose harness or wire somewhere.

 

I am currently having a similar issue. When running the air conditioner I've noticed the passenger side gets cold but the driver side is luke warm. If move the control slider to hot it does get hot. I hope somebody has the solution.

 

Add freon ASAP, it is low.