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My truck's a snake!

my 2002 chevy s-10 started making an air/hissing noise inside the cab. It seems to be coming from around the air conditioner controls (center front). It hisses while running, whether moving or not, does not change when the air conditioner or fan is running or not, but does improve when accelerating quickly. What could this be and would it be an easy fix or a professional job (my husband restores old cars, but doesn’t do a lot with the newer ones)?

Your chevy uses engine vacuum to operate the AC controls. I’m sure that you will find that something in the heat/AC is not working, like a blend door of switching the outlet from the floor to the dash or defrost. The reason is that one of the vacuum lines has come loose and that is the hissing noise that you are hearing.