Dodge Omni/Horizon/Rampage 1978-1989 Repair Guide

Evaporator Case

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REMOVAL & INSTALLATION



1978-79 Models

WARNING
If a refrigerant recovery/recycling machine is not available, this job should be performed at a dealer or a shop that has this equipment. During installation, a small can of refrigerant oil will be necessary.

  1. Properly discharge the air conditioning system into a recovery/recycling machine.
  2.  
  3. Disconnect the negative battery cable.
  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. Part the temperature door cable from the heater-evaporator unit.
  2.  
  3. Disconnect the temperature door cable from the retaining clips.
  4.  
  5. Remove the glove box.
  6.  
  7. Disconnect the vacuum harness from the control head.
  8.  
  9. Disconnect the blower motor lead and anti-diesel relay wire.
  10.  
  11. Remove the seven screws fastening the right trim bezel to the instrument panel. Starting at the right side, swing the bezel clear and remove it.
  12.  
  13. Remove the three screws on the bottom of the center distribution duct cover and slide the cover rearward and remove it.
  14.  
  15. Remove the center distribution duct.
  16.  
  17. Remove the defroster duct adaptor.
  18.  
  19. Remove the H-type expansion valve, located on the right side of the firewall:
  20.  
    1. Remove the 5 / 16 in. bolt in the center of the plumbing sealing plate.
    2.  
    3. Carefully pull the refrigerant lines toward the front of the car, taking care to avoid scratching the valve sealing surfaces.
    4.  
    5. Remove the two 1 / 4 -20 Allen head cap screws and remove the valve.
    6.  

  21. Cap the pipe openings at once. Wrap the valve in a plastic bag.
  22.  
  23. Disconnect the hoses from the core tubes.
  24.  
  25. Disconnect the vacuum lines at the intake manifold and water valve.
  26.  
  27. Remove the unit-to-firewall retaining nuts.
  28.  
  29. Take off the panel support bracket.
  30.  
  31. Remove the right cowl lower panel.
  32.  
  33. Take off the instrument panel pivot bracket screw from the right side.
  34.  
  35. Remove the screws securing the lower instrument panel at the steering column.
  36.  
  37. Pull back the carpet from under the unit as far as possible.
  38.  
  39. Remove the nut from the evaporator-heater unit-to-plenum mounting brace and blower motor ground cable. While supporting the unit, remove the brace from its stud.
  40.  
  41. Lift the unit, pulling it rearward to allow clearance. These operations may require two people.
  42.  
  43. Slowly lower the unit taking care to keep the studs from hanging-up on the insulation.
  44.  
  45. When the unit reaches the floor, slide it rearward until it is out from under the instrument panel.
  46.  
  47. Remove the unit from the car.
  48.  

To install:


WARNING
When installing the unit in the car, care must be taken that the vacuum lines to the engine compartment do not hang-up on the accelerator or become trapped between the unit and the firewall. If this happens, kinked lines will result and the unit will have to be removed to free them. Proper routing of these lines will require two people. The portion of the vacuum harness which is routed through the steering column support MUST be positioned BEFORE the distribution housing is installed. The harness MUST be routed ABOVE the temperature control cable.

  1. Place the unit on the floor as far under the panel as possible.
  2.  
  3. Raise the unit carefully, at the same time pull the lower instrument panel rearward as far as possible.
  4.  
  5. Position the unit in place and attach the brace to the stud.
  6.  
  7. Install the lower ground cable and attach the nut.
  8.  
  9. Install and tighten the unit-to-firewall nuts.
  10.  
  11. Reposition the carpet and install, but do not tighten the right instrument panel pivot bracket screw.
  12.  
  13. Place a piece of sheet metal or thin cardboard against the evaporator-heater assembly to center the assembly duct seal.
  14.  
  15. Position the center distributor duct in place making sure that the upper left tab comes in through the left center air conditioning outlet opening and that each air take-off is properly inserted in its respective outlet.
  16.  


WARNING
Make sure that the radio wiring connector does not interfere with the duct.

  1. Install and tighten the screw securing the upper left tab of the center air distribution duct to the instrument panel.
  2.  
  3. Take out the sheet metal or cardboard from between the unit and the duct.
  4.  


WARNING
Make sure that the unit seal is properly aligned with the duct opening.

  1. Install and tighten the two lower screws fastening the center distribution duct to the instrument panel.
  2.  
  3. Place and tighten the screws securing the lower instrument panel at the steering column.
  4.  
  5. Install and tighten the nut securing the instrument panel to the support bracket.
  6.  
  7. Make sure that the seal on the unit is properly aligned and seated against the distribution duct assembly.
  8.  
  9. Tighten the instrument panel pivot bracket screw and install the right cowl lower trim.
  10.  
  11. Slide the distributor duct cover assembly onto the center distribution duct so that the notches lock into the tabs and the tabs slide over the rear and side ledges of the center duct assembly.
  12.  
  13. Install the three screws securing the ducting.
  14.  
  15. Install the right trim bezel.
  16.  
  17. Join the vacuum harness to the control head.
  18.  
  19. Connect the blower lead and the anti-diesel wire.
  20.  
  21. Install the glove box.
  22.  
  23. Connect the temperature door cable.
  24.  
  25. Install new O-rings on the evaporator plate and the plumbing plate. Coat the new O-rings with clean refrigerant oil.
  26.  
  27. Place the H-valve against the evaporator sealing plate surface, then install the two 1 / 2 -20 through-bolts. Tighten to 6-10 ft. lbs. (8-14 Nm).
  28.  
  29. Carefully hold the refrigerant line connector against the valve, then install the 5 / 16 -18 bolt. Tighten to 14-20 ft. lbs. (19-27 Nm).
  30.  
  31. Install the heater hoses at the core tubes.
  32.  
  33. Connect the vacuum lines at the manifold and water valve.
  34.  
  35. Install the condensate drain tube.
  36.  
  37. Have the system evacuated, charged and leak tested by a trained technician.
  38.  

1980-89 Models

WARNING
If a refrigerant recovery/recycling machine is not available, this job should be performed at a dealer or a shop that has this equipment.

  1. Properly discharge the air conditioning system into a recovery/recycling machine.
  2.  
  3. Drain the cooling system.
  4.  


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 negative battery cable.
  2.  
  3. Disengage the heater hoses at the core tubes. Cap the tube openings to prevent spillage.
  4.  
  5. Separate the vacuum lines at the intake manifold and the water valve. Tag the lines for installation.
  6.  
  7. Remove the ""H" valve:
  8.  
    1. Disconnect the wire from the low pressure cut-off switch.
    2.  
    3. Remove the bolt in the center of the plumbing sealing plate.
    4.  
    5. Pull the refrigerant line assembly toward the front of the car. Take care to avoid scratching the valve sealing surfaces with the tube pilots.
    6.  
    7. Hold the ""H" valve, remove the two Allen head screws and lift out the valve.
    8.  

  9. Unclamp and remove the condensation drain.
  10.  
  11. Remove the nuts holding the heater/evaporator case to the firewall.
  12.  
  13. Depress the tab and unhook the cable retainer from the case.
  14.  
  15. Remove the glove compartment.
  16.  
  17. Disconnect the vacuum harness from the air conditioning control head.
  18.  
  19. Separate the blower feed wire and the anti-diesel solenoid wires.
  20.  
  21. Remove the seven screws retaining the right trim bezel to the instrument panel. Starting at the right side, swing the trim bezel clear of the panel and remove it.
  22.  
  23. Remove the three screws securing the center distribution duct to the instrument panel and remove it.
  24.  
  25. Remove the defroster duct adapter.
  26.  
  27. Take off the instrument panel support bracket.
  28.  
  29. Remove the instrument panel pivot bracket screw from the right side.
  30.  
  31. Extract the screws securing the instrument panel to the steering column.
  32.  
  33. Pull the carpet away from the case.
  34.  
  35. Remove the nut securing the case to the plenum and ground cable.
  36.  
  37. Support the case and remove the plenum bracket.
  38.  
  39. Lift the case and pull it rearward as far as possible to clear the panel. The lower panel may have to be pulled rearward to aid in case removal.
  40.  


WARNING
Two people will make this job a lot easier.

  1. When the case clears the panel, lower it slowly so that the studs don't hang up in the panel liner.
  2.  
  3. Lower the case to the floor and remove it from the car.
  4.  


WARNING
When installing the unit, make sure that none of the vacuum lines are kinked. Kinked lines would require removal of the unit again.

  1. Place the case on the floor as far forward as possible.
  2.  
  3. Lift the unit being careful of the studs. Manipulate the panel to aid installation of the case.
  4.  

To install:

  1. Attach the brace to the stud. Install the ground wire and tighten the nut.
  2.  
  3. Install and tighten the case-to-firewall nuts.
  4.  
  5. Connect the drain tube.
  6.  
  7. Install the heater hoses.
  8.  
  9. Install the vacuum lines.
  10.  
  11. Install the ""H" valve.
  12.  
  13. Reposition the carpet.
  14.  
  15. Install, but don't tighten the right side instrument panel pivot bracket screw.
  16.  
  17. Install the defroster duct adapter, making certain that the opening is properly aligned.
  18.  
  19. Place a piece of thin cardboard against the evaporator/heater assembly-to-center distribution duct seal.
  20.  
  21. Position the center distribution duct in place. Make sure that the upper left tab comes out through the left center duct. Each end air outlet must be properly aligned with its respective spot cooler.
  22.  


WARNING
Be certain that the radio wiring connector does not interfere with the center duct.

  1. Install and tighten the screw retaining the upper left tab of the center duct.
  2.  
  3. Remove the cardboard. Make sure that the evaporator/heater seal is properly aligned with the top of the center duct opening.
  4.  
  5. Install and tighten the two lower center duct-to-panel screws.
  6.  
  7. Install all remaining parts in the reverse of the removal sequence. Fill the cooling system. Evacuate, charge and leak test the air conditioning system.
  8.  

 
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