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Davo
Davo, Master technician
Category: Car
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Experience:  ASE Master Technician/Advanced Automotive Diagnostic Technician
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i change the heater core on an 1985 K5 Blazer 305 cu in w/ air 4 wd

Customer Question

how do i change the heater core on an 1985 K5 Blazer
305 Cu in w/ air 4 wd
Submitted: 12 years ago.
Category: Car
Expert:  Davo replied 12 years ago.
 

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. Disconnect the heater hoses at the core tubes and drain the engine coolant. Plug the core tubes to prevent spillage.

Remove the nuts from the distributor air ducts in the engine compartment.


  1. Remove the glove compartment and door.



  2. 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.



  3. Disconnect the Air-Defrost and Temperature door cables.



  4. If equipped, remove the nuts from the three selector duct studs projecting through the dash panel.



  5. Remove the floor outlet and remove the defroster duct-to-heater distributor screw.



  6. 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.



  7. Remove the heater distributor module from the truck.



  8. Remove the heater core retaining straps and remove the core.



  9. 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.


Click image to see an enlarged view
Fig. 1: Heater distributor without A/C shown



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



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



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



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



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



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



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Fig. 8: Remove any cable fasteners



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



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



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



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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. 13: Remove the heater core retaining bolts



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



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