GM Full-Size Trucks 1980-1987 Repair Guide

Heater Core

Print

REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15

  1. Disconnect the battery ground cable.
  2.  
  3. Disconnect the heater hoses at the core tubes and drain the engine coolant. Plug the core tubes to prevent spillage.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the nuts from the distributor air ducts in the engine compartment.
  2.  
  3. Remove the glove compartment and door.
  4.  
  5. If equipped with A/C, remove the center duct to selector duct and instrument panel screws and remove the center lower and center upper ducts.
  6.  
  7. Disconnect the Air-Defrost and Temperature door cables.
  8.  
  9. If equipped, remove the nuts from the three selector duct studs projecting through the dash panel.
  10.  
  11. Remove the floor outlet and remove the defroster duct-to-heater distributor screw.
  12.  
  13. Remove the heater distributor-to-instrument panel screws. Pull the assembly rearward to gain access to the wiring harness and disconnect the wires attached to the unit.
  14.  
  15. Remove the heater distributor module from the truck.
  16.  
  17. Remove the heater core retaining straps and remove the core.
  18.  
  19. Installation is the reverse of removal. Be sure that the core-to-core and case-to-dash panel sealer is intact. Fill the cooling system and check for leaks.
  20.  



Click image to see an enlarged view

Fig. Fig. 1: Heater distributor without A/C shown



Click image to see an enlarged view

Fig. Fig. 2: Loosen the clamps, then carefully disconnect the heater hoses from the core pipes protruding through the cowl



Click image to see an enlarged view

Fig. Fig. 3: After removing the retaining screws, remove the glove box assembly from the instrument panel



Click image to see an enlarged view

Fig. Fig. 4: Remove the various heater module-to-instrument panel fasteners



Click image to see an enlarged view

Fig. Fig. 5: Remove the heater module-to-cowl fasteners



Click image to see an enlarged view

Fig. Fig. 6: Remove the ash tray in order to access the module fasteners



Click image to see an enlarged view

Fig. Fig. 7: Lower the module assembly slightly for access to the hoses and cables



Click image to see an enlarged view

Fig. Fig. 8: Remove any cable fasteners



Click image to see an enlarged view

Fig. Fig. 9: Using a small prytool or a pair of pliers, remove the cable locktabs, then separate the cables from the module levers



Click image to see an enlarged view

Fig. Fig. 10: With the module removed from the truck remove the module cover bolts



Click image to see an enlarged view

Fig. Fig. 11: Don't forget the cover bolts near the flap which are hard to access



Click image to see an enlarged view

Fig. Fig. 12: When all of the bolts have been removed, carefully lift the cover from the module



Click image to see an enlarged view

Fig. Fig. 13: Remove the heater core retaining bolts



Click image to see an enlarged view

Fig. Fig. 14: Remove the bolt and the heater core clamp



Click image to see an enlarged view

Fig. Fig. 15: Lift the heater core and retaining strap from the module

 
label.common.footer.alt.autozoneLogo