Chrysler RAM50/D50/Arrow 1979-1993 Repair Guide

Heater Core

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The heater core is a small heat exchanger located inside the vehicle, similar to the radiator at the front of the vehicle. Coolant is circulated from the engine through the heater core and back to the engine. The heater fan blows fresh, outside air through the heater core; the air is heated and sent on to the interior of the vehicle.

About the only time the heater core will need removal is for replacement due to clogging or leaking. Thankfully, this doesn't happen too often; removing the heater core is a major task. Some are easier than others, but all require working in unusual positions inside the vehicle and fitting tools into very cramped quarters behind the dashboard. In many cases, the dashboard must be removed during the procedure -another major project.

REMOVAL & INSTALLATION



1979-86 Models

See Figure 1

  1. Disconnect the battery ground cable.
  2.  
  3. Move the temperature selector lever to the off position.
  4.  
  5. Drain the coolant.
  6.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by 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. In the cab, remove the parcel tray, the center vent grille and duct and the defroster duct.
  2.  



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Fig. Fig. 1: Heater system components-1983-86 models

  1. Label and disconnect the control cables at the heater box.
  2.  
  3. Disconnect the coolant hoses running to the heater core. There will be some coolant within the hoses; don't spill it in the cab.
  4.  
  5. Disconnect the fan wiring. Remove the upper and center mounting nuts holding the heater assembly. Remove the assembly.
  6.  


WARNING
The heater core still contains coolant; be careful not to spill it in the cab.

  1. With the heater case removed, the core may be easily removed on the workbench.
  2.  
  3. Place the new core in the heater case. Install the case in position and tighten the retaining nuts and bolts. Make sure the case is properly seated before tightening the mounting nuts.
  4.  
  5. Connect the wiring to the fan motor.
  6.  
  7. Install the water hoses, making sure each is pushed onto its pipe at least 1 in. (25mm). Use new clamps if needed.
  8.  
  9. Connect the cables to the heater unit. Pay attention to the labels.
  10.  
  11. Install the defroster duct, the center ventilator duct and grille and the parcel tray.
  12.  
  13. Double check the draincock, closing it securely if not already done. Fill the cooling system with coolant.
  14.  
  15. Connect the negative battery cable.
  16.  
  17. Start the engine. Move the temperature selector to HOT and allow the engine to warm up. Check the function of each heater control and inspect the hose connections for leaks.
  18.  

1987-93 Models See Figures 2 through 7

  1. With the engine cold, set the temperature control lever to the extreme hot position. Drain the engine coolant through the radiator drain plug.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by 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 coolant hoses running to the heater pipes at the firewall. Take note of hose location and placement; they are formed to fit exactly as needed.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the hazard flasher switch.
  6.  
  7. Pop out the hole cover, or starter unlock switch, on the opposite side (from the hazard flasher switch) of the instrument hood.
  8.  
  9. Remove the instrument hood.
  10.  
  11. Remove the instrument cluster, remembering to disconnect the wiring and speedometer cable at the rear.
  12.  
  13. Remove the fusebox cover. Remove the fusebox from the dashboard and let it hang.
  14.  
  15. Remove the glove box. Move the stopper out of the way before lowering the door.
  16.  
  17. Remove the two defroster ducts.
  18.  
  19. Label and disconnect the 3 control wires running to the heater unit.
  20.  
  21. Remove the speaker cover panels on each side.
  22.  
  23. Remove the clock or small compartment from the dash.
  24.  
  25. Pop out the small square cover at the upper center of the dash. Its easiest to reach in the clock hole and release the clips with your fingers.
  26.  
  27. Remove the lower center faceplate or cover from the center of the dash.
  28.  



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Fig. Fig. 2: Heater unit assembly components-1987-93 models



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Fig. Fig. 3: Instrument panel (dashboard) removal and installation components-1987-93 models



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Fig. Fig. 4: Unfasten the four retaining screws to remove the meter hood-1987-93 models



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Fig. Fig. 5: To remove the glove box assembly, the glove box stopper must first be released-1987-93 models



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Fig. Fig. 6: Make certain to remove all of the instrument panel retaining screws before removing the panel-1987-93 models

  1. Remove the shifter knob.
  2.  
  3. Remove the floor console assembly.
  4.  
  5. Disconnect the left side and front harness connectors running to the dashboard.
  6.  
  7. Disconnect the air conditioner and heater wiring harnesses. Disconnect the instrument cluster harness and the radio connectors, including the antenna wire.
  8.  
  9. Remove the retaining nuts and bolts holding the dash. They are located across the top, along the sides and at the bottom.
  10.  
  11. Use the tilt release lever and move the steering column all the way downward.
  12.  
  13. Remove the dash carefully; several components are still connected to it.
  14.  
  15. Remove the large duct running between the heater case and the fan case.
  16.  
  17. Remove the center ventilator duct.
  18.  
  19. Remove the defroster duct.
  20.  
  21. Remove the two vertical reinforcing bars.
  22.  
  23. Remove the retaining nuts and bolts and remove the heater case.
  24.  


WARNING
The heater core still contains coolant; be careful not to spill it inside the cab.

  1. Remove the hose cover on the side of the heater case.
  2.  
  3. Disconnect the hose clamps on the small hoses.
  4.  



Click image to see an enlarged view

Fig. Fig. 7: Remove the joint hose clamps (1), joint hoses (2) and plate (3) before removing the heater core-1987-93 models

  1. Use a sharp knife or razor to cut away the small hoses. Attempting to remove the hoses may damage the tubing.
  2.  
  3. Remove the retaining plate.
  4.  
  5. Remove the heater core from the case.
  6.  

To install:
  1. Install the core into the case, making sure all the padding and insulation is in place.
  2.  
  3. Install the plate holding the two pipes. Install new small hoses and new clamps. Make certain the joints are correctly fitted and that the clamps are tightened. These hoses are not accessible after installation; any leak will require removal again.
  4.  
  5. Install the hose cover.
  6.  
  7. Install the heater unit in the vehicle, making certain the pipes go through the firewall grommet correctly. Tighten the retaining bolts and nuts.
  8.  
  9. Install the center reinforcements for the dash.
  10.  
  11. Install the defroster duct, the center vent duct and the large air duct to the blower.
  12.  
  13. Place the dash into the vehicle carefully and connect the main electrical harnesses.
  14.  
  15. Install all the retaining nuts and bolts but do not tighten any of them until the alignment of the dash is correct.
  16.  
  17. Reinstall the floor console, the shifter knob and the lower center faceplate.
  18.  
  19. Install the upper bolt cover in the center of the dash.
  20.  
  21. Replace the clock or small pocket. Don't forget to plug wiring together.
  22.  
  23. Install the speaker covers.
  24.  
  25. Route the heater control cables properly and connect them.
  26.  
  27. Install the defroster ducts.
  28.  
  29. Install the glove box.
  30.  
  31. Remount the fusebox on the dash and install the lid.
  32.  
  33. Install the instrument cluster. Connect the speedometer cable and wiring harnesses before tightening the screws.
  34.  
  35. Install the instrument cluster hood and install the bolt cover.
  36.  
  37. Install the hazard warning switch.
  38.  
  39. Connect the heater hoses to the pipes at the firewall.
  40.  
  41. Double check the draincock, closing it securely if not already done. Fill the cooling system with coolant.
  42.  
  43. Connect the negative battery cable.
  44.  
  45. Start the engine. Move the temperature selector to HOT and allow the engine to warm up. Check the function of each heater control and inspect the hose connections for leaks.
  46.  

 
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