How do you replace a heater core in an 86 Chevy Silverado pickup?

Answer

I recently replaced the heater core in my 1985 Chev C-30 Silverado 1 Ton Pickup with air conditioning. First I had remove any of the parts that are connected to the basic plenum inside the cab(where the core is installed). I then had to remove the passenger side fender well (Not as difficult as it sounds). Then I had to remove the outside cover for the heater and air conditioning cores in the engine compartment (The bottom screw in this cover is not accessible until you remove the fender well). Then it is necessary to remove the three nuts for the through studs that come from inside the cab and go through the firewall. There is one at the top and two at the bottom (again you can't get at one of the bottom nuts unless the fender well is removed). I then had to remove the A/C core (just a few bolts all accessible with the wheel well removed) in order to remove a speed nut from the upper stud. The heater plenum (with the heater core inside) can now be pulled away from the firewall far enough to reach behind and disconnect any remaining vacuum lines and electrical fittings. The plenum can now be removed from the vehicle. There is still considerable work to replace the core. The firewall side of the plenum is all one piece and all the screws have to be removed including two hidden screws on the left side of the opening in the plenum underneath the foam gasket. It is also necessary to remove any thing that attaches the two halves of the plenum together. Shaft for the ? gate is just pushed out and the screw in the linkage that connects the ? gate with the vacuum controller has to be removed while holding the gate open and using a 1/4 drive extension with the proper size socket. Sorry I don't know what these gates are called but there is only one of each so you can readily identify them. You now can remove the inner half and the heater core is exposed with its two tie down brackets. Good Luck.

First answer by Rich Harp. Last edit by Rich Harp. Question popularity: 101 [recommend question]