I bought A 97 blazer(s-10). Here is the reason the ac does not work,according to her: She had no heat or "defrost" in the winter.Shop found problem and said it was expensive.They could fix the heat/defrost problem fairly cheap but she would no longer have a working ac system.This is what she chose.With all dials "off" heat still blows in.. does anyone have a clue at all what they might have done? Maybe I could reverse it for the summer? Thanks,Dave

 

Your heat and a/c are two completly different systems. All I can figure is they might have moved a ground or power wire around for the control panel.

 

I bet they moved the temperature door to full heat. The temp door is electric. There are quite a few posts where I have attached vacuum diagrams and a schematic of how the HVAC system airflow works.

 

True, that would explain the constant heat. And that heat would override the A/C temperature-wise

 

I will start searching threads on the electrical side of things.Thanks for helping me get started in this adventure

 

searching the forums I think I will shoot for the temperature door.Is there any test I can do to check it? From what I gather it should be under the glove box.

 

It is located on the top of the HVAC housing accessible by dropping the glove box down out of the way. It can be a royal pain to get to with the dash in place, but it can be done.

As far as testing it, I would start by seeing if it is connected and still there. Most common, the actuator itself fails, but there are some cases where the temperature door inside the HVAC housing breaks.

 

k..weekend project, with a few others Thanks for the info. D