Isuzu Cars and Trucks 1981-1991

Heater Core

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REMOVAL AND INSTALLATION
RWD I-Mark

The heater core is located inside the heater system under the instrument panel. The steering column and instrument panel have to be removed.

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the radiator coolant into a suitable container.
  4.  


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. Disconnect the hoses at the core connections and plug the hoses. They are located inside the engine compartment.
  2.  
  3. Remove the outer blower unit case cover and disconnect the fresh air door cable. Disconnect the temperature cable at the water valve.
  4.  
  5. Remove the steering column as outlined in .
  6.  
  7. Remove the instrument cluster as outlined in this Section.
  8.  
  9. Disconnect the console wiring and remove the console as outlined in this Section.
  10.  
  11. Remove the heater control and plate as outlined in this Section.
  12.  
  13. Remove the glove box.
  14.  
  15. Disconnect the selector mode cable from the driver side of the heater unit.
  16.  
  17. Carefully pull the temperature and fresh air door cables through the cowl and remove the control panel through the cluster opening.
  18.  
  19. Remove instrument panel assembly as outlined in this Section.
  20.  
  21. Remove the heater unit through bolt located at the rear of the unit.
  22.  
  23. Remove the four attaching nuts holding the heater unit to the blower unit and remove the heater unit.
  24.  
  25. Remove the bolts holding the heater unit case halves together and remove heater core.
  26.  



Click image to see an enlarged view

Fig. Heater core RWD I-Mark

To install:

  1. Install the core and bolts holding the heater unit case halves together.
  2.  
  3. Install the heater unit and four attaching nuts holding the heater unit to the blower unit. Make sure the seal is in place. Water will leak, if not.
  4.  
  5. Install the heater unit through bolt located at the rear of the unit.
  6.  
  7. Install instrument panel assembly as outlined in this Section.
  8.  
  9. Carefully thread the temperature and fresh air door cables through the cowl and install the control panel through the cluster opening.
  10.  
  11. Connect the selector mode cable to the driver side of the heater unit.
  12.  
  13. Install the glove box.
  14.  
  15. Install the heater control and plate as outlined in this Section.
  16.  
  17. Connect the console wiring and install the console as outlined in this Section.
  18.  
  19. Install the instrument cluster as outlined in this Section.
  20.  
  21. Install the steering column as outlined in .
  22.  
  23. Install the outer blower unit case cover and connect the fresh air door cable. Connect the temperature cable at the water valve.
  24.  
  25. Connect the hoses at the core connections. Do not overtighten the hose clamps.
  26.  
  27. Refill the radiator with coolant.
  28.  
  29. Connect the negative battery cable and check for leaks.
  30.  

FWD I-Mark
  1. Disconnect the negative battery cable.
  2.  
  3. Drain the engine coolant into a suitable container.
  4.  


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. Disconnect the heater hoses from the core. Be careful not to damage the core by pulling on the hose to remove. Cut the hoses if they will not come off easily. Use a prybar to carefully pry open the lower part of the unit case.
  2.  
  3. Remove the retaining clips, lower heater unit case and core assembly.
  4.  

To install:

  1. Install the core, being careful not to damage the assembly.
  2.  
  3. Install the lower heater unit case, retaining clips and connect the heater hoses.
  4.  
  5. Refill the engine with coolant and check for leaks.
  6.  



Click image to see an enlarged view

Fig. Heater core FWD I-Mark

RWD Impulse
  1. Disconnect the negative battery cable.
  2.  
  3. Drain the engine coolant into a suitable container.
  4.  


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 instrument panel and glove compartment as outlined in this Section.
  2.  
  3. Remove the air conditioning line and plug so contamination does not enter the system.
  4.  
  5. Disconnect the heater hoses. Be careful not to damage the core by pulling on the hose to remove. Cut the hoses if they will not come off easily.
  6.  
  7. Remove the evaporator assembly, blower assembly and heater unit.
  8.  
  9. Disassembly the heater unit be prying the retaining clips and split the unit in half. Remove the heater core from the unit.
  10.  



Click image to see an enlarged view

Fig. Heater core RWD Impulse

To install:

  1. Install the heater core, making sure all the seals are in place.
  2.  
  3. Assemble the heater unit, making sure all the seals are in place.
  4.  
  5. Install the evaporator assembly, blower assembly and heater unit.
  6.  
  7. Connect the heater hoses. Be careful not to damage the core by pulling on the hoses.
  8.  
  9. Install the air conditioning line, evacuate, leak test and recharge the air conditioning system.
  10.  
  11. Install the instrument panel and glove compartment as outlined in this Section.
  12.  
  13. Refill the engine coolant into a suitable container.
  14.  
  15. Connect the negative battery cable.
  16.  

FWD Impulse and Stylus
  1. Disconnect the negative battery cable.
  2.  
  3. Drain the engine coolant into a suitable container.
  4.  


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. Disconnect the heater hoses. Be careful not to damage the core by pulling on the hose to remove. Cut the hoses if they will not come off easily.
  2.  
  3. Remove the instrument panel as outlined in this Section.
  4.  
  5. Disconnect the resistor assembly.
  6.  
  7. Remove the duct (non air conditioning) or the evaporator housing (air conditioning). If equipped with air conditioning, refer to for discharging, evacuating and recharging the air conditioning system.
  8.  
  9. Remove the center vent duct and heater unit.
  10.  
  11. Disassemble the heater unit by removing the duct, mode control case, core assembly and heater core.
  12.  



Click image to see an enlarged view

Fig. Heater core FWD Impulse and Stylus

To install:

  1. Install the heater core, making sure all the seals are in place.
  2.  
  3. Assemble the heater unit, making sure all the seals are in place.
  4.  
  5. Install the center vent duct and heater unit.
  6.  
  7. Install the duct (non air conditioning) or the evaporator housing (air conditioning). If equipped with air conditioning, refer to for discharging, evacuating and recharging the air conditioning system.
  8.  
  9. Connect the resistor assembly.
  10.  
  11. Install the instrument panel as outlined in this Section.
  12.  
  13. Connect the heater hoses. Be careful not to damage the core by pulling on the hose to remove. Cut the hoses if they will not come off easily.
  14.  
  15. Refill the engine coolant.
  16.  
  17. Connect the negative battery cable and check for leaks.
  18.  

P'up, Amigo, Rodeo and Trooper
  1. If equipped with A/C have the system discharged by a shop with the proper equipment and certificaion.
  2.  


NOTE
If your vehicle is equipped with air conditioning, refer to General Information and Maintenance for information regarding the implications of servicing your A/C system yourself. Only a MVAC-trained, EPA-certified, automotive technician should service the A/C system or its components.

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the engine coolant into a suitable container.
  4.  


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. Disconnect the heater hoses. Be careful not to damage the core by pulling on the hose to remove. Cut the hoses if they will not come off easily.
  2.  
  3. Remove the instrument panel as outlined in this Section.
  4.  
  5. Disconnect the resistor assembly.
  6.  
  7. If possible, disconnect and move the duct (non air conditioning) or the evaporator housing (air conditioning) to the right to gain clearance for the heater unit. If equipped with air conditioning, do not disconnect air conditioning system until absolutely necessary. Refer to for discharging, evacuating and recharging the system.
  8.  
  9. Remove the instrument panel stay and heater unit.
  10.  
  11. Disassemble the heater unit by removing the duct, mode control case, core assembly and heater core.
  12.  



Click image to see an enlarged view

Fig. Heater core P'up, Amigo and Rodeo



Click image to see an enlarged view

Fig. Heater core Trooper



Click image to see an enlarged view

Fig. Removing the heater core from the case

To install:

  1. Assemble the heater unit by installing the duct, mode control case, core assembly and heater core.
  2.  
  3. Install the heater unit and instrument panel stay.
  4.  
  5. Connect the duct (non air conditioning) or the evaporator housing (air conditioning) to the heater unit. Have the A/C systems evacuated and recharged if the system was discharged to remove the evaporator assembly.
  6.  
  7. Connect the resistor assembly.
  8.  
  9. Install the instrument panel as outlined in this Section.
  10.  
  11. Connect the heater hoses. Be careful not to damage the core by pulling on the hose.
  12.  
  13. Refill the engine coolant into a suitable container.
  14.  
  15. Connect the negative battery cable and check for leaks.
  16.  

 
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