Hey Mark, Is the the dash control moving the slider too far?
Mine will also hiss air if I turn the knob to the off position too far.
I have to turn the switch on just a little bit to the on to make it stop hissing.
Mine is not rebuilt (yet) and I would think that its not suppose to do that after a rebuild.
Maybe cable is sticking?
Just a thought....... Jeff


1956 GMC 102
1952 Chevy hardtop
1932 plymouth PB 3 window coupe
1980 H-D FXWG