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    Honda Accord/Prelude 1984-1995 Repair Guide

    Heater Core

    Print

    REMOVAL & INSTALLATION



    See Figures 1 and 2



    Click image to see an enlarged view

    Fig. Fig. 1: The heater core is secured to the unit by clamps



    Click image to see an enlarged view

    Fig. Fig. 2: After the clamps are removed, the core can be extracted from the unit

    1984-85 Accord and 1984-87 Prelude

    See Figures 3 and 4

    1. Disconnect the negative battery cable.
    2.  
    3. Drain the coolant from the radiator.
    4.  
    5. From under the dash, remove the heater pipe cover and clamp.
    6.  
    7. Remove the heater core retaining plate.
    8.  
    9. Place a drip pan under the heater pipe connections.
    10.  



    Click image to see an enlarged view

    Fig. Fig. 3: Heater assembly used on 1984-85 Accords. Note the heater valve is located on the side of the assembly

    1. Pull out the cotter pin of the joint hose clamp and separate the heater pipes. Some coolant will run out, be sure to have the drip pan in place.
    2.  



    Click image to see an enlarged view

    Fig. Fig. 4: Heater assembly found on 1984-87 Preludes

    1. Pull the heater core from the heater housing.
    2.  

    To install:
    1. Slide the heater core into the housing.
    2.  
    3. Connect the heater pipes. Use new clamps if necessary.
    4.  
    5. Install the heater core retaining plate. Tighten the screws until snug.
    6.  
    7. Install the heater pipe cover and clamp.
    8.  
    9. Fill the cooling system.
    10.  
    11. Start the engine. Turn the heater on and check for leaks.
    12.  

    1986-89 Accord

    See Figures 5 and 6

    1. Disconnect the negative battery cable.
    2.  
    3. Drain coolant from the radiator. Put a drain pan underneath the hose connections at the firewall. Note the hose locations, then disconnect the two hoses.
    4.  
    5. Disconnect the heater valve cable from the valve. Remove the two lower heater mounting nuts.
    6.  



    Click image to see an enlarged view

    Fig. Fig. 5: Heater mounting on models with pushbutton controls

    1. On push button type heaters, disconnect the cool vent cable at the heater. On lever type heaters, disconnect the function cable and the air mix cable from the heater.
    2.  



    Click image to see an enlarged view

    Fig. Fig. 6: Heater mounting on models with lever controls

    1. Remove the dashboard.
    2.  
    3. Remove the heater ducts.
    4.  
    5. On pushbutton type heaters, disconnect the air mix cable from the heater and the wiring harness from the connector.
    6.  
    7. Remove the bolts, then pull the heater assembly away from its mounts.
    8.  
    9. Remove the screws securing the heater core, then slide the core out of the heater assembly.
    10.  

    To install:
    1. Install the heater core into the heater assembly. Tighten the screws securing the heater core until snug.
    2.  
    3. Position the heater assembly on its mounts, then tighten the retaining bolts.
    4.  
    5. On pushbutton type heaters, connect the air mix cable and engage the wiring harness connector.
    6.  
    7. Install the heater ducts.
    8.  
    9. Install the dashboard.
    10.  
    11. On push button type heaters, connect the cool vent cable at the heater. On lever type heaters, connect the function cable and the air mix cable to the heater.
    12.  
    13. Install the two lower heater mounting nuts.
    14.  
    15. Connect the heater valve cable to the valve. Connect the hoses to the heater core; use new clamps as necessary.
    16.  
    17. Refill the cooling system. Start the engine and check for leaks.
    18.  

    1990-93 Accord

    See Figure 7

    1. Disconnect the negative battery cable. If so equipped, disable the Supplemental Restraint System (SRS).
    2.  
    3. Drain the engine coolant.
    4.  
    5. Label and disconnect the heater hoses at the firewall. Be prepared to contain spilled coolant from the hoses and fittings.
    6.  
    7. Disconnect the heater valve control cable from the valve.
    8.  
    9. Remove the dashboard.
    10.  



    Click image to see an enlarged view

    Fig. Fig. 7: Heater assembly used on 1990-93 Accords

    1. Remove the dashboard support pipe.
    2.  
    3. Remove the 4 mounting bolts, then remove the heater assembly.
    4.  
    5. Remove the heater core cover and the clamp securing the heater core.
    6.  
    7. Remove the core from the heater assembly.
    8.  

    To install:
    1. Slide the core into the heater assembly.
    2.  
    3. Install the heater core clamp and cover.
    4.  
    5. Position the heater assembly in the vehicle and secure it with the mounting bolts.
    6.  
    7. Install the dashboard support pipe.
    8.  
    9. Install the dashboard.
    10.  
    11. Connect the heater control valve cable to the valve.
    12.  
    13. Connect the heater hoses at the firewall.
    14.  
    15. Refill the engine coolant.
    16.  
    17. If applicable, enable the SRS.
    18.  
    19. Connect the negative battery cable. Start the engine and check for leaks.
    20.  

    1994-95 Accord

    See Figures 8 and 9

    1. Disconnect the battery cables, then disable the Supplemental Restraint System (SRS).
    2.  
    3. Drain the engine coolant.
    4.  
    5. Label and disconnect the heater hoses at the firewall. Be prepared to contain spilled coolant from the hoses and fittings.
    6.  
    7. Disconnect the heater valve control cable from the valve.
    8.  
    9. Remove the two heater unit mounting nuts from inside the engine compartment.
    10.  
    11. Remove the dashboard.
    12.  
    13. Remove the mounting nuts and bolts securing the steering hanger beam and brackets, then remove the beam and brackets from the vehicle.
    14.  



    Click image to see an enlarged view

    Fig. Fig. 8: Steering hanger beam and bracket assemblies

    1. Remove the heater duct (on cars without air conditioning) or the evaporator case (cars with air conditioning).
    2.  
    3. Unplug the mode control motor connector.
    4.  
    5. Remove the mounting bolt, then remove the heater unit from the vehicle.
    6.  



    Click image to see an enlarged view

    Fig. Fig. 9: After the final mounting bolt has been removed, the heater unit can be removed from the vehicle

    1. Remove the clips and screws securing the vent/defroster duct, then remove the duct.
    2.  
    3. Remove the heater core and pipe clamps, then remove the core from the unit.
    4.  

    To install:
    1. Position the heater core in the unit, then secure it with the core and pipe clamps.
    2.  
    3. Install the vent/defroster duct on the heater unit.
    4.  
    5. Position the heater unit in the vehicle, then secure it with the mounting bolt. Engage the mode control motor connector.
    6.  
    7. Install the heater duct or evaporator case as applicable.
    8.  
    9. Install the steering hanger beam and brackets in the vehicle. Tighten the nuts/bolts to 16 ft. lbs. (22 Nm).
    10.  
    11. Install the dashboard.
    12.  
    13. Install the two heater unit mounting nuts in the engine compartment. Tighten them to 16 ft. lbs. (22 Nm).
    14.  
    15. Connect the heater control valve cable to the valve.
    16.  
    17. Connect the heater hoses at the firewall.
    18.  
    19. Refill the engine coolant.
    20.  
    21. Enable the SRS, then connect the battery cables. Start the engine and check for leaks.
    22.  

    1988-91 Prelude

    See Figure 10

    1. Disconnect the negative battery cable.
    2.  
    3. Drain the engine coolant.
    4.  
    5. Label and disconnect the heater hoses at the firewall.
    6.  
    7. Disconnect the heater valve cable from the heater valve.
    8.  
    9. Remove the dashboard.
    10.  
    11. Remove the heater duct.
    12.  
    13. Remove the lower mounting nuts holding the heater.
    14.  
    15. Remove the steering column bracket.
    16.  



    Click image to see an enlarged view

    Fig. Fig. 10: Heater unit mounting on 1988-91 Preludes

    1. Remove the two remaining mounting bolts holding the heater. Disconnect the wiring from the function control motor. Remove the heater assembly.
    2.  
    3. Remove the integrated control unit and bracket from the case.
    4.  
    5. Remove the 2 screws, bracket, retaining plate and the heater core cover.
    6.  
    7. Remove the heater core cover, setting plate and clamp.
    8.  
    9. Carefully pull the heater core from the housing.
    10.  

    To install:
    1. Install the heater core into the case. Install the setting plate and the clamp.
    2.  
    3. Install the core cover, set plate and bracket.
    4.  
    5. Install the integrated control unit and bracket.
    6.  
    7. Fit the heater assembly into the vehicle. Apply a sealant around the grommets.
    8.  
    9. Install the upper two mounting bolts, tightening them to 7 ft. lbs. (10 Nm).
    10.  
    11. Install the steering column bracket.
    12.  
    13. Install the lower mounting nuts, tightening them to 16 ft. lbs. (22 Nm).
    14.  
    15. Install the heater duct.
    16.  
    17. Install the dashboard.
    18.  
    19. Connect the hoses at the firewall fittings. Use new clamps. Make certain the hoses are on their correct fittings.
    20.  
    21. Connect the heater valve cable.
    22.  
    23. Refill the coolant. Start the engine and check for leaks.
    24.  

    1992-95 Prelude

    See Figures 11 and 12

    1. Disconnect the battery cables, then disable the Supplemental Restraint System (SRS).
    2.  
    3. Drain the engine coolant.
    4.  
    5. Label and disconnect the heater hoses at the firewall. Be prepared to contain spilled coolant from the hoses and fittings.
    6.  
    7. Disconnect the heater valve control cable from the valve.
    8.  
    9. Remove the two heater unit mounting nuts from inside the engine compartment.
    10.  



    Click image to see an enlarged view

    Fig. Fig. 11: Remove the two nuts securing the heater unit in the engine compartment

    1. Remove the dashboard.
    2.  
    3. Remove the heater duct (on cars without air conditioning) or the evaporator case (cars with air conditioning).
    4.  
    5. Remove the mounting bolts, then remove the heater unit from the vehicle.
    6.  



    Click image to see an enlarged view

    Fig. Fig. 12: Heater unit mounting bolt locations

    1. Remove the screws securing the vent/defroster duct, then remove the duct.
    2.  
    3. Remove the heater core and pipe clamps, then remove the core from the unit.
    4.  

    To install:
    1. Position the heater core in the unit, then secure it with the core and pipe clamps.
    2.  
    3. Install the vent/defroster duct on the heater unit.
    4.  
    5. Position the heater unit in the vehicle, then secure it with the mounting bolts.
    6.  
    7. Install the heater duct or evaporator case as applicable.
    8.  
    9. Install the dashboard.
    10.  
    11. Install the two heater unit mounting nuts in the engine compartment. Tighten them to 16 ft. lbs. (22 Nm).
    12.  
    13. Connect the heater control valve cable to the valve.
    14.  
    15. Connect the heater hoses at the firewall.
    16.  
    17. Refill the engine coolant.
    18.  
    19. Enable the SRS, then connect the battery cables. Start the engine and check for leaks.
    20.  

     
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