Chevrolet Repair: AC Control, montecarlo, guru

Question
My 2005 Montecarlo has dual temp controls.  The left one has no effect on changing the temp. Can move it up or down and temp stays the same on that side. Will not heat at all. The right ones works as advertised and warms the right side. Thanks for your input on this.  You may not know about AC but if you do thanks.

Answer
Hi Howard.... well your right i am not an A/C guru...but if one side is fine then i would look at the heater/ac control for the side that doesn't... if control is electric check for power if it has vacum check for vacum loss...i know it's not much but i hope this helps