GM Cadillac Deville_Fleetwood_ELD_Seville 1990-1998

Heater Core

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The heater core is the main component of the heater system. The heater core is located inside of the heater and evaporator module. Engine coolant is pumped into the heater core from the engine whenever the engine is operating. The heater core fins transfer the heat from the engine coolant to the air passing over the heater core. The heater core has specific inlet and outlet tubes. The placement of the heater hoses should be noted prior to servicing the heater core or the heater hoses.

REMOVAL & INSTALLATION



Catera
  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Disconnect the heater hose quick disconnects from the heater core pipes.
  6.  



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Fig. Heater hose quick disconnections



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Fig. Removing the retaining bracket screw

  1. Pull back on the sleeve to unlock, then carefully pull back to remove. Tabs on the quick disconnects break easily, use caution.
  2.  

  1. Remove the steering column.
  2.  
  3. Remove the instrument panel carrier assembly.
    1. Complete removal of the I/P carrier from the vehicle is not necessary. Once the I/P carrier is unfastened, carefully pull it back from the HVAC module until sufficient heater core access is possible.
    2.  

  4.  
  5. Unscrew the blower motor housing screws.
  6.  
  7. Remove the blower motor housing with the motor attached.
  8.  



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Fig. Remove the support brace bolt

  1. Detach the heater core pipe bracket by removing the screw.
  2.  
  3. Remove the heater core inlet and outlet pipe retaining bracket screw, and remove the pipes.
  4.  
  5. Unbolt the instrument panel support brace bolt from the I/P.
  6.  
  7. Remove the instrument panel support brace bolt from the transmission well (floor panel).
  8.  
  9. Remove the instrument panel support brace.
  10.  
  11. Unscrew the support bracket bolt.
  12.  
  13. Remove the instrument panel support bracket.
  14.  
  15. Remove the heater core retaining screw.
  16.  
  17. Remove the heater core and rubber seal.
    1. Plug the ports to prevent spillage of coolant on the interior trim.
    2.  
    3. Remove the heater core first, then the rubber seal from the cavity.
    4.  

  18.  



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Fig. Remove the heater core (2) with the rubber seal (1)

To install:

  1. Install the rubber seal into the heater core cavity
    1. Ensure the rubber heater core seal is in position before installing the heater core.
    2.  

  2.  
  3. Install the heater core
    1. Use caution when installing the heater core into the cavity to prevent damage to the fins.
    2.  

  4.  
  5. Tighten the heater core retaining screws until they are fully seated and not striped.
  6.  
  7. Install the instrument panel support bracket and tighten the bolt to 16 ft. lbs. (22 Nm).
  8.  
  9. Install the instrument panel support brace to the transmission well (floor panel) and the instrument panel. Tighten the bolts to 16 ft. lbs. (22 Nm).
  10.  
  11. Attach the heater core inlet and outlet pipes.
    1. Use new rubber O-rings and lightly lubricate with coolant to aid installation.
    2.  
    3. Install the heater core inlet and outlet pipe retaining bracket and tighten the screw to 44 inch lbs. (5 Nm).
    4.  

  12.  
  13. Install the heater core pipe bracket and tighten the screw until fully seated and not stripped.
  14.  
  15. Replace the blower motor housing with the motor attached and tighten the screws to 35 ft. lbs. (4 Nm).
  16.  
  17. Install the instrument panel carrier assembly.
  18.  
  19. Install the steering column.
  20.  
  21. Attach the heater hose quick disconnects to the heater core pipes.
    1. Ensure the quick disconnects are fully seated and that the retaining sleeves are pushed to the locked. position.
    2.  

  22.  
  23. Refill the cooling system and check for leaks.
  24.  
  25. Connect the negative battery cable.
  26.  

Deville and Fleetwood
  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant.
  4.  


CAUTION
Never open, service, or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. In addition, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Disconnect the heater core hoses using tool J-37097 or equivalent.
  2.  
  3. Remove the right side sound insulator and the glove box module.
  4.  
  5. Remove the programmer shield, if equipped, and disconnect the air mix valve link.
  6.  
  7. Disconnect the programmer vacuum and electrical connectors.
  8.  
  9. Remove the heater core cover, leaving the programmer attached.
  10.  
  11. Remove the heater core retaining screws and the heater core.
  12.  

To install:

  1. Position the heater core and secure with the retaining screws.
  2.  
  3. Install the heater core cover.
  4.  
  5. Connect the programmer vacuum and electrical connectors.
  6.  
  7. Connect the air mix valve link and, if equipped, install the programmer shield.
  8.  
  9. Connect the heater core hoses.
  10.  
  11. Connect the negative battery cable and fill the cooling system.
  12.  
  13. Adjust the air mix valve as follows:
    1. Set the temperature on the heater and A/C control panel to 90°F (32°C). Allow 1-2 minutes for the programmer arm to travel to the maximum heat position.
    2.  
    3. Unsnap the threaded rod from the plastic retainer on the programmer output arm.
    4.  
    5. Check the air mix valve for free travel. Push the valve to the maximum A/C position and check for binding.
    6.  
    7. Preload the air mix valve in the maximum heat position by pulling the threaded rod to ensure the valve is sealing. The programmer output arm should be in the maximum heat position.
    8.  
    9. Snap the threaded rod into the plastic retainer on the programmer arm. Avoid moving the programmer arm or air mix valve.
    10.  
    11. Set the temperature on the control panel to 60°F (16°C). Verify that the programmer arm and the air mix valve travel to the maximum cold position.
    12.  

  14.  
  15. Install the right side sound insulator and the glove box module.
  16.  

Eldorado and Seville
  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Remove the glove box unit and right side lower sound insulator.
  6.  
  7. Remove the programmer as follows:
    1. Remove the 2 PCM bracket screws. Position the PCM aside to gain access to the rear programmer mounting screw.
    2.  
    3. Disconnect the threaded rod from the programmer.
    4.  
    5. Remove the vacuum connector retaining nut.
    6.  
    7. Disconnect the vacuum and wiring connectors from the programmer.
    8.  
    9. Remove the 3 screws and the programmer.
    10.  

  8.  
  9. On early model vehicles, proceed as follows:
    1. Disconnect the wiring connectors from the BCM and PCM and remove the mounting brackets.
    2.  

  10.  
  11. Remove the heater core cover.
  12.  
  13. Disconnect the heater hoses from the heater core.
  14.  
  15. Remove the 2 heater core retaining screws and remove the heater core.
  16.  

To install:

  1. Install the heater core to the heater case and secure with the 2 screws.
  2.  
  3. Connect the heater hoses to the heater core.
  4.  
  5. Install the heater core cover.
  6.  
  7. On early model vehicles, proceed as follows:
    1. Install the PCM mounting bracket and PCM. Connect the wiring connectors to the PCM.
    2.  
    3. Install the BCM mounting bracket and BCM. Connect the wiring connectors to the BCM.
    4.  

  8.  
  9. Install the programmer as follows:
    1. Install the programmer in the vehicle and connect the vacuum and wiring connectors.
    2.  
    3. Install the vacuum connector retaining nut.
    4.  
    5. Connect the threaded rod to the programmer.
    6.  
    7. Return the PCM to its original position and secure with the 2 bracket screws.
    8.  

  10.  
  11. Connect the negative battery cable and fill the cooling system.
  12.  
  13. Adjust the air mix valve as follows:
    1. Set the temperature on the heater and A/C control panel to 90°F (32°C). Allow 1-2 minutes for the programmer arm to travel to the maximum heat position.
    2.  
    3. Unsnap the threaded rod from the plastic retainer on the programmer output arm.
    4.  
    5. Check the air mix valve for free travel. Push the valve to the maximum A/C position and check for binding.
    6.  
    7. Preload the air mix valve in the maximum heat position by pulling the threaded rod to ensure the valve is sealing. The programmer output arm should be in the maximum heat position.
    8.  
    9. Snap the threaded rod into the plastic retainer on the programmer arm. Avoid moving the programmer arm or air mix valve.
    10.  
    11. Set the temperature on the control panel to 60°F (16°C). Verify that the programmer arm and the air mix valve travel to the maximum cold position.
    12.  

  14.  
  15. Install the right side lower sound insulator and the glove box unit.
  16.  

 
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