BMW Coupes and Sedans 1970-1988 Repair Guide

Heater Assembly and Core

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REMOVAL & INSTALLATION



1983-88 524td, 528e, 533i, 535i, 633CSi, 635CSi, M5 and M6 Models

  1. Disconnect the battery ground. Remove the instrument panel trim at the bottom left. Remove the package tray.
  2.  
  3. Have the air conditioning system discharged by a professional using an approved recovery/recycling machine.
  4.  
  5. Remove the 2 bolts securing the trim panel underneath the evaporator unit.
  6.  
  7. Remove the tape type insulation.
  8.  
  9. Using a backup wrench, disconnect the low and high pressure A/C lines and cap the open ends.
  10.  
  11. Unfasten the electrical connector for the evaporator. Disconnect the temperature sensor plug accessible from the outside of the evaporator housing.
  12.  
  13. Remove the 2 bolts and then remove the bracket that braces the evaporator housing at the firewall. Remove the mounting bolt from either side of the housing.
  14.  
  15. Unclip both fasteners and remove the housing.
  16.  
  17. Now, move into the engine compartment and remove the rubber insulator from the cowl.
  18.  
  19. Remove the mounting bolts for the cover which is located under the windshield.
  20.  
  21. Remove the mounting nuts for the heater housing located on either side of the blower.
  22.  
  23. Drain the cooling system, then disconnect the 2 hoses at the core.
  24.  


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and are could 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. Working from inside the vehicle, remove the 3 electrical connectors for the heater housing. Pull off the 2 air ducts.
  2.  
  3. Remove the 2 mounting nuts and remove the heater unit.
  4.  
  5. Remove the air duct connections from the housing. Push the retaining bar back and then split and remove the 2 blower shells.
  6.  
  7. Remove the retaining clips from the housing halves and split the housing. Then, remove the core.
  8.  

To install:
  1. Reverse the removal procedure, noting the following points:
    1. Cement a new rubber seal on to the core.
    2.  
    3. Make sure that when reassembling the halves of the housing, all the distributor door flap shafts pass through the holes in the housing.
    4.  
    5. Before reconnecting the refrigerant lines, coat the threads with clean refrigerant oil.
    6.  
    7. Refill the cooling system with clean coolant and bleed it.
    8.  
    9. Have the air conditioning system evacuated and recharged using an approved recovery/recycling machine.
    10.  

  2.  

 
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