I have a 2003 Monte Carlo SS and I'm having a problem with the heat,fan,air,defrost controls... I'm in Texas and I need this to work.

When i start the car I can sometimes change the controls. If i change the fan speed nothing happens. When things are not working i can't turn on defrost, turn on/off the ac button, or change the air circulation from fresh air or re-circulate.

Also when this happens the outdoor temp module is blank until the ac/heat controls come on. I have not idea what this could be and can't find anything on the issue.

 

i would try to replace the relay for the fan and see if that works some times in a rarity the relay goes with out warning. also check the fuse for it as well

 

Sorry to read about your problem
How many miles on your Monte Carlo ?
Is your radiator clean ? When was it last serviced ?
Your Heater Core could be cloged ?
I would check your heat sensor, blower motor resistor. Check wiring for shorts/breaks..
Do you have any electrical mod's done to your Monte ?

I hope one of our expert tech member's reads your thread and can help/advise...Good Luck

 

I think that it could be one of two items...the first would be the control head itself..where the fan controls/ AC controls are located......looks like the unit maybe bad...the second would be the BCM...this unit controls almost all of the electrical items on your Monte.....if this unit begins to fail you will have all sorts of electrical anomolies occur...see if you can substitute the heater/AC head unit with another first before you fool around with the BCM which requires dealer programming.