Hi All.. On my 89 IROC the heater controls are not working. The blower motor switch works and the hot/cold works. But when I move the selector switch for the heat/vent/AC nothing..stays blowing out the defroster and the AC is not kicking on. Even when I put the selector on AC, the compressor will not come on. Is there anyway that you can check the control switch to tell if it's bad? Thank You and God Bless US All...John

 

Defrost is the default when there's a vacuum leak (which is often at the switch):

https://www.thirdgen.org/forums/elec...ml#post5278772

I'd guess the AC is a separate issue. Perhaps the system requires a charge.

JamesC

 

Hi All:
I have since replaced all the vaccum hoses and still will not switch off the defrost. I have even bypassed all the vaccum and hooked it straight to the heater. Still no luck.. Probably the control unit then?? I have looked at the unit, but have not taken it out. How do you disconnect the hot/cold control from it? Thank You and God Bless US All...John

 

Follow the link I provide above.

JamesC