GM Caprice 1990-1993 Repair Guide

Heater Core

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REMOVAL & INSTALLATION



1990

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: A/C module and heater core servicing - 1990

The heater core is accessible through the engine compartment, by removing the upper A/C housing assembly located in the right rear of the engine compartment.

  1. Disconnect the negative battery cable. Drain the cooling system then, disconnect and plug the hoses at the heater core. Cut the hose to facilitate removal, if necessary.
  2.  


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 blower motor assembly.
  2.  
  3. Remove the hood-to-cowl seal in the area of the A/C module.
  4.  
  5. Remove both halves of the air inlet screen (fresh air vent screen).
  6.  
  7. Remove the right side wiper arm.
  8.  
  9. Remove the module ground strap.
  10.  
  11. Disconnect and tag the connectors from the blower motor, resistor, blower relay and the thermostatic switch.
  12.  
  13. Remove the upper case half to lower case half cowl attaching screws.
  14.  
  15. Remove the heater core to case attaching screw and pull up firmly to release the core from the spring loaded clip. Remove the heater core from the vehicle.
  16.  

To install:
  1. Line up the core base with the clip at the bottom of the case before you insert the core. The top retaining bracket will line up with the hole at the top of the core when properly seated.
  2.  
  3. Install the new core in the spring loaded clip and install the core to case mounting screws.
  4.  
  5. Install the case cover making sure that cover is completely seated in the sealer.
  6.  
  7. Install the upper case half to the lower half and tighten the mounting screws.
  8.  
  9. Install the leaf screen. Install the wiring harness in the retainer on the casing.
  10.  
  11. Connect the wiring and diagnostic connector at the casing.
  12.  
  13. Connect the heater hoses to the core and fill the cooling system.
  14.  
  15. Connect the negative battery cable, run the engine and check the heater operation.
  16.  

1991-93

See Figure 2



Click image to see an enlarged view

Fig. Fig. 2: A/C module and heater core servicing - 1991-93

  1. Disconnect the negative battery cable. Drain the cooling system into a suitable container.
  2.  


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 screw holding the hose assembly to the cowl panel.
  2.  
  3. Release the quick connect fittings, on the inlet and outlet pipes of the heater core, by squeezing both release tabs at the base of the heater core tube and pulling on the pipe to disengage the fitting.
  4.  
  5. From inside vehicle, remove the four retaining screws on the upper right side sound insulator. Pull the insulator straight back until the two locator studs are disengaged.
  6.  
  7. Remove the nut from the shroud panel stud on the Instrument panel lower reinforcement.
  8.  
  9. Remove the screw from the instrument panel carrier and remove the instrument panel lower reinforcement.
  10.  
  11. Disconnect both vacuum harness connectors, then remove the connector halves from the lower evaporator case and position the harnesses out of the way.
  12.  
  13. Remove the right side hinge pillar finish (kick) panel by pulling it away from the body pillar.
  14.  
  15. Roll the carpeting back enough to provide access to the lower area of the A/C module.
  16.  
  17. Remove the seven screws attaching the lower case to the module.
  18.  

The forward center attaching screw may be difficult find. It is located almost directly below the lower right side heater core tube, the screw head is straight down from the A/C vacuum tank, using a1/4in. drive 7mm socket with a swivel adaptor and short extension on a ratchet handle will aid in the removal.

  1. Remove the lower evaporator case.
  2.  
  3. Remove the heater core mounting straps and screws.
  4.  
  5. Carefully pull the heater core rearward, working the heater core tubes out of the seal.
  6.  

To install:
  1. Transfer the quick connect tabs to the new heater core.
  2.  
  3. Insert heater core into position, carefully pushing the tubes through the seal. Install the mounting straps and screws.
  4.  
  5. Install the lower evaporator case and tighten attaching screws evenly.
  6.  
  7. Fit the carpeting back into place.
  8.  
  9. Connect both vacuum connectors and install assembled connectors to the lower case.
  10.  
  11. With the instrument panel lower reinforcement held into position, install the nut to the shroud panel stud (tighten to 89 inch lbs.) and install the screw to the instrument panel carrier (tighten to 89 inch lbs.).
  12.  
  13. Snap the right side hinge pillar finish trim (kick) panel into place.
  14.  
  15. Slide the sound insulator forward into position engaging both locator tabs, and install the four attaching screws.
  16.  
  17. Hold the control valve and hose assembly into position, align the quick connect fitting tabs with the grooves in the fitting sleeve.
  18.  
  19. Push the sleeve into place on the heater core tube, then pull back on the sleeve to check for proper connection. Repeat for other connector.
  20.  
  21. Install the heater outlet pipe retaining screw. Fill with coolant, start engine and check for leaks and proper heater operation.
  22.  

 
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