Chevrolet Full Size Cars 1979-1989

Heater Core

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REMOVAL & INSTALLATION





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Fig. Fig. 1 Heater air flow schematic



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Fig. Fig. 2 Exploded view of an early model heater module



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Fig. Fig. 3 Loosen the clamps retaining the hoses to the heater core tubes.



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Fig. Fig. 4 Remove the rubber seal from the module top cover



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Fig. Fig. 5 Loosen and remove the module cowl screen retainers



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Fig. Fig. 6 With all of the fasteners removed, carefully lift the screen from the top of the module



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Fig. Fig. 7 Some vehicles may use a multi-layered screen. If so, remove the lower layers



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Fig. Fig. 8 Disengage the blower motor electrical wiring



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Fig. Fig. 9 Tag and disengage any electrical connectors from the heater module



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Fig. Fig. 10 If equipped with air conditioning, make sure all related connectors are disengaged and repositioned out of the way



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Fig. Fig. 11 Loosen the retainers holding any electrical components to the outside of the module cover



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Fig. Fig. 12 Remove and reposition the cover mounted components



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Fig. Fig. 13 Loosen and remove the cover retaining screws



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Fig. Fig. 14 Some screws may be difficult to access without the proper driver extensions



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Fig. Fig. 15 Be sure remove all of cover retaining screws



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Fig. Fig. 16 Some screws may be difficult to find, such as these located down inside the air intake.



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Fig. Fig. 17 Once all of the bolts are removed, break the seal by lifting the top cover from the module



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Fig. Fig. 18 With the top cover removed, the heater core and the evaporator are exposed for service



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Fig. Fig. 19 If not done already, disconnect the heater hoses from the core tubes



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Fig. Fig. 20 Loosen and remove the heater core retaining bracket



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Fig. Fig. 21 Carefully lift the core from the module, but remember it may still contain a fair amount of coolant

  1. Disconnect the negative battery cable, then drain the engine cooling system to a level below heater core.
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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. Disconnect and plug the heater hoses at the core tubes. Plugging the hoses will help prevent excessive coolant leakage.
  2.  
  3. If applicable, remove the diagnostic connector plug-to-heater case screws.
  4.  
  5. Tag and disengage the connectors from the blower motor, resistor, blower relay and the thermostatic switch, as applicable. If equipped, remove the air conditioner wiring harness from the blower case shroud.
  6.  
  7. Remove the module rubber seal, then loosen the leaf screen assembly screws and remove the screen from the top of the module.
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  9. If equipped and necessary, remove the accumulator bracket screws.
  10.  
  11. Loosen the retainers and remove the module's top cover. Be careful, on most models there are hard to find screws such as those located inside the air intake near the case separation points. The cover is sealed to the module and this seal must be broken before the cover can be removed. Be absolutely sure that all cover fasteners are removed before attempting to break the seal or cover damage will result. Take your time and be careful not to force and crack or otherwise damage the cover.
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  13. With the case opened, loosen or unclip the core retainer, then carefully lift the core from the vehicle.
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To install:

  1. Thoroughly clean the mating surfaces of the cover and the module of all old sealer.
  2.  
  3. Install the heater core to the module and secure the retaining bracket.
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  5. Apply a coating of sealant to the cover, then install the cover and tighten the fasteners.
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  7. If applicable, install the accumulator bracket screws.
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  9. Install the module screen and rubber seal.
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  11. Engage and secure the electrical connectors and components to the module cover, as noted during removal.
  12.  
  13. Remove the plugs and reconnect the heater hoses to the core tubes.
  14.  
  15. Connect the negative battery cable, then properly refill the engine cooling system and check for leaks.
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