Nissan Z - ZX 1970-1988 Repair Guide

Heater Core

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REMOVAL & INSTALLATION



1970-78 Models
WITHOUT AIR CONDITIONING

See Figures 1, 2 and 3

The entire heater unit MUST BE removed for access to the heater core.

  1. Disconnect the negative battery cable and drain the engine coolant.
  2.  
  3. Remove the floor console.
  4.  



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Fig. Fig. 1: Exploded view of heater assembly-1970-78 models



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Fig. Fig. 2: Disconnect the heater door rod-1970-78 models



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Fig. Fig. 3: To remove the heater assembly, unfasten the nuts from the engine compartment firewall and the bolts from inside the vehicle

  1. Remove the finish panel around the heater control retaining screws and pull the panel out slightly. Disconnect the wires and remove the panel.
  2.  
  3. Remove the duct-to-instrument panel bracket screws and the brackets screws, then the brackets. Disconnect the ventilator duct hose from the ventilator outlet, then remove the outlet from the center panel.
  4.  
  5. To remove the heater control, perform the following procedures:
    1. Remove the control cables at the air intake duct, the heat control valve and the floor heater door, then disconnect the door control rod.
    2.  
    3. Disconnect the wires from the heater control to the heater harness at the connectors.
    4.  
    5. Remove the control assembly-to-instrument panel screws.
    6.  
    7. Remove the heater control panel reinforcement-to-instrument panel screws and the reinforcement.
    8.  
    9. Remove the heater control-to-heater unit screws.
    10.  

  6.  
  7. Disconnect the defroster ducts from the heater unit. Remove the heater inlet and outlet clamps and hoses, then the hoses from the tubes.
  8.  
  9. Remove the duct adapter-to-heater unit screws.
  10.  
  11. Remove the heater unit-to-firewall nuts/screws. The nuts are on the engine side of the firewall; the screws are under the heater control unit.
  12.  
  13. Pull the heater out slightly and turn it 90° to the left. Remove the heater unit from the instrument panel.
  14.  
  15. Loosen the hose clamps on the heat control valve and disconnect the hoses.
  16.  
  17. Remove the two screws retaining the valve to its bracket.
  18.  
  19. Remove the heater bracket screws (from the unit) and the bracket.
  20.  
  21. Remove the capillary tube bracket-to-unit screws and the capillary tube from the unit. Remove the valve at the same time.
  22.  


WARNING
Be careful not to bend or twist the tube too much. If the tube must be bent slightly, be sure the valve is open to prevent any change in the operating characteristics of the capillary tube.

  1. Remove the heat control valve bracket-to-unit screws and the hose connector from the unit.
  2.  
  3. Loosen the hose clamps from the heater core tubes and disconnect the hoses from the core tubes. Remove the heat control valve bracket and the hose connector.
  4.  
  5. Disconnect the floor door operating rod from the door.
  6.  
  7. Remove the side cover from the unit.
  8.  
  9. Open the floor door to prevent scratching the heater core and remove the core from the unit.
  10.  
  11. To assemble and install, reverse the removal procedures. Adjust the air intake door, the mode door, the floor door and the heat control valve cables so that:
    1. When the AIR lever is OFF , the air intake door is closed.
    2.  
    3. When the AIR lever is on HEAT , the mode door lever is moved toward the firewall.
    4.  
    5. When the AIR lever is on DEF , the floor door lever is pushed forward toward the firewall to the defrost position.
    6.  
    7. When the TEMP lever is on HOT , the heat control valve is open (pulled towards you).
    8.  

  12.  

WITH AIR CONDITIONING
  1. Disconnect the negative battery cable.
  2.  
  3. Drain the engine coolant.
  4.  
  5. Working in the engine compartment, loosen the heater hose clamps and pull the hoses from the tubes.
  6.  
  7. Remove the blower housing, using the procedure given earlier in this section.
  8.  
  9. To remove the heater control valve, perform the following procedures:
    1. Move the TEMP lever to HOT .
    2.  
    3. Remove the hoses from the valve.
    4.  
    5. Remove the valve-to-bracket screws. Be careful not to twist or bend the capillary tube excessively.
    6.  
    7. Remove the vacuum valve-to-heater core outlet hose.
    8.  
    9. Remove the vacuum valve and the heater valve bracket screws.
    10.  
    11. Remove the vacuum hose, then the vacuum valve and heater valve bracket as an assembly.
    12.  

  10.  
  11. Disengage the control cable from the heater door and remove the rod from the door.
  12.  
  13. Remove the heater core cover screws and the cover. Pull the core from the housing. Keep the heater door open when doing this to prevent damage to the core.
  14.  
  15. To assemble and install, reverse the removal procedures.
  16.  

1979-88 Models
WITHOUT AIR CONDITIONING

See Figure 4

The heater unit MUST BE removed for access to the heater core.

  1. Disconnect the negative battery cable.
  2.  
  3. Set the TEMP lever to HOT and drain the coolant.
  4.  
  5. Remove the instrument panel lower covers, the floor nozzles, the defroster ducts, the instrument console and the center ventilator.
  6.  



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Fig. Fig. 4: Bolts which secure the heater unit to the firewall are accessible through the instrument panel opening-1979-88 models without air conditioning

  1. Remove the glove box and the heater duct.
  2.  
  3. Remove the control cables and rod from the heater unit. Remove the heater control assembly attaching screws and the control assembly.
  4.  
  5. Disconnect the heater inlet and outlet hoses inside the passenger compartment.
  6.  
  7. Remove the blower assembly. Refer to the procedure in this section.
  8.  
  9. Remove the heater unit-to-firewall bolts and the unit. All the bolts are on the passenger compartment side of the firewall and are accessible through the center of the instrument panel opening.
  10.  
  11. Remove the heat control valve.
  12.  
  13. Remove the clips from the heater case seam and separate the case. Remove the core.
  14.  
  15. To assemble and install, reverse the removal procedures.
  16.  

WITH AIR CONDITIONING

See Figures 5, 6 and 7

To perform this procedure, the refrigerant must be removed and replaced. This requires the use of an approved recovery/recycling machine, as well as specific training and licensing. If necessary, consult a professional.

  1. Disconnect the negative battery cable. Set the TEMP lever to HOT and drain the coolant.
  2.  
  3. Remove the blower unit using the procedure given earlier in this section.
  4.  



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Fig. Fig. 5: 280 ZX heater assembly

  1. To remove the cooling unit, perform the following:
    1. Discharge the cooling system.
    2.  
    3. Loosen the flare nuts at each of the inlet and outlet pipe connections at the evaporator. Plug the openings immediately to prevent the entry of moisture or dirt.
    4.  
    5. Remove the passenger side defroster duct.
    6.  
    7. Remove the mounting bolts and the cooling unit from beneath the instrument panel.
    8.  

  2.  
  3. To remove the heater controls, perform the following:
    1. Remove the lower instrument panel trim covers.
    2.  
    3. Remove the console.
    4.  
    5. Remove the ventilator and the duct from the center of the instrument panel.
    6.  
    7. Disconnect the cable from the heat control valve.
    8.  
    9. Disconnect the wiring connector. Disconnect and label the vacuum hoses or the connections of the vacuum selector.
    10.  
    11. Remove the attaching screws and the control assembly.
    12.  

  4.  
  5. Remove the instrument panel lower cover and the floor nozzle on the driver's side.
  6.  
  7. Disconnect the heater inlet and outlet hoses.
  8.  
  9. Remove the heater unit-to-firewall bolts and the unit.
  10.  
  11. Remove the heat control valve.
  12.  
  13. Remove the clips from the heater case seam and separate the two halves of the case.
  14.  
  15. Remove the heater core.
  16.  
  17. To assemble and install, reverse the removal procedures. Adjust the heat control cables.
  18.  



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Fig. Fig. 6: 300 ZX heater assembly



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Fig. Fig. 7: Unfasten the upper retainer screws when removing a ZX heater assembly

 
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