I found my answer by google but I'd like to hear something from you gentlemen.

just bought my truck I love it.. 1998 LT blazer 95000 miles

anyways the AC doesn't work.. it blows hot air whether I have the AC on , Fan on blows hot air in from outside etc.. how is the fixable? i do t k ow if this could make the truck over heat but i read about a Heater valve switch is open behind the glovebox?

 

The repair depends on what is causing the condition and the equipment you have.

Do you have auto climate control?

When you turn on your A/C, does the compressor run at all? If you jumper the power & ground to the compressor clutch, does it cool?

 

Yes the part is called blend door actuator. New about $150. Not easy to get to, but you can get to it by pulling the dash down. It's kinda of square shaped and has a shaft going through it that opens the flapper for switching heat and cold air.