GM-GMC: 1992 s-10 heater control, vacuum leak, vacum

Question
Hello! I have a 1992 s-10 2wd 4.3 that i just picked up, and im having a problem with the heater/ac control. It wont switch functions and emitts a constant vacum leak sound. I know its a vacum leak, and its a vacum controlled system, but is it repairable? Or do i have to replace the whole switch? (a new one costs more than i payed for the truck!) i tryed removing it to look at it, but can only gte it out about 1/2 inch and cant see much....Any thoughts on removal and or repair of it? Thanks! Scott

Answer
They are a vacuum operated system.  You will need to get to the back side of it to locate the leak and repair it before anything else.  It has been a while since I worked on anything like that but if the control is mounted under the radio you may be able to access the back of it better if you remove the radio.  You are on the right track though, solve the vacuum leak problem or replace it with a used one it will be cheaper.
Hope that helps