Heater core shut off valve installed

[beamn7]

My 85 Silverado doesn't have a heater control valve either. Just a blend door in the hvac unit....
Alot of motorhomes and stepvans still use the manual / cable operated heater control valve....
CJLINKSTER, your truck was not equipped with A/C from the factory. As mentioned, you have a Sanden compressor and the evaporator is not outside the firewall in the split case as a factory unit would be. May have been added at the dealer level. Was not uncommon to have that done....