GM Prizm/Nova 1985-1993 Repair Guide

Evaporator Unit and Expansion Valve

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REMOVAL & INSTALLATION




CAUTION
Please re-read the air conditioning section in Routine Maintenance so that the system may be discharged properly. Always wear eye protection and gloves when discharging the system. Observe no smoking/no open flame rules.

1985-88

See Figures 1 and 2

  1. Disconnect the negative battery cable.
  2.  
  3. Safely discharge the air conditioning system.
  4.  
  5. Disconnect the suction tube from the evaporator assembly, then disconnect the liquid line from the assembly. Cap the open fittings immediately to prevent the entry of dirt and moisture.
  6.  



Click image to see an enlarged view

Fig. Fig. 1: Evaporator assembly - 1985-88

  1. Remove the grommets from the inlet and outlet fittings.
  2.  
  3. Remove the glove box.
  4.  
  5. Remove the lower cover from under the dashboard.
  6.  
  7. Disconnect the air conditioning switch connector.
  8.  
  9. Disconnect the vehicle wiring harness at the connector.
  10.  
  11. Remove the 4 nuts and 3 bolts securing the cooling assembly and remove the evaporator assembly from the car.
  12.  
  13. Remove the air conditioning amplifier.
  14.  
  15. Remove the air conditioning wiring harness from the case.
  16.  
  17. Remove the 5 clamps and 2 screws and remove the lower casing.
  18.  
  19. Remove the 2 screws holding the upper casing and remove the casing.
  20.  



Click image to see an enlarged view

Fig. Fig. 2: Separating the evaporator case halves - 1985-88

  1. Remove the heat insulator and clamp from the outlet tube.
  2.  
  3. Disconnect the liquid line tube from the inlet fitting of the expansion valve.
  4.  
  5. Disconnect the expansion valve from the inlet fitting of the evaporator.
  6.  
  7. Remove the pressure switch if necessary.
  8.  
  9. Inspect the evaporator fins for blockage. Check all the fittings for cracks or scratches.
  10.  

To install:
  1. To reassemble, connect the expansion valve to the inlet fitting of the evaporator and tighten the nut to 17 ft. lbs.
  2.  
  3. Connect the liquid line tube to the inlet fitting of the expansion valve.
  4.  
  5. Install the pressure switch, if removed, and tighten it to 10 ft. lbs.
  6.  
  7. Install the clamp and heat insulator to the outlet tube.
  8.  
  9. Assemble the upper and lower cases onto the evaporator unit.
  10.  
  11. Reinstall the thermistor if it was removed.
  12.  
  13. Install the air conditioning wire harness onto the evaporator unit.
  14.  
  15. Install the air conditioning amplifier.
  16.  
  17. Place the assembled unit in place inside the car and install the retaining nuts and bolts.
  18.  


WARNING
Be careful not to pinch the wiring harness(es) during installation.

  1. Connect the air conditioning switch.
  2.  
  3. Connect the vehicle wiring harness to the connector.
  4.  
  5. Install the glove box and the under-dash cover.
  6.  
  7. Install the grommets on the inlet and outlet fittings.
  8.  
  9. Connect the liquid line to the evaporator inlet fitting and tighten it to 10 ft. lbs. Make sure the rubber washer (O-ring) is present inside the line and make certain the joint is correctly threaded before tightening it. Do not overtighten the joint.
  10.  
  11. Connect the suction tube to the evaporator unit outlet fitting and tighten it to 24 ft. lbs. Again, make sure the rubber washer (O-ring) is present inside the line and make certain the joint is correctly threaded before tightening it. Do not overtighten the joint.
  12.  
  13. If the evaporator was replaced with a NEW unit, add 1.5 oz. of compressor oil to the compressor. This replaces oil in the system removed with the old evaporator.
  14.  
  15. Connect the negative battery cable.
  16.  
  17. Evacuate and recharge the air conditioning system.
  18.  

1989-90

See Figure 3

  1. Disconnect the negative battery cable.
  2.  
  3. Safely discharge the air conditioning system.
  4.  
  5. Disconnect the suction tube from the evaporator assembly, then disconnect the liquid line from the assembly. Cap the open fittings immediately to prevent the entry of dirt and moisture.
  6.  
  7. Remove the grommets from the inlet and outlet fittings.
  8.  
  9. Remove the glove box.
  10.  
  11. Disconnect the wiring harness connectors.
  12.  
  13. Remove the 4 nuts and 4 screws holding the evaporator unit. Remove the unit through the front of the instrument panel.
  14.  
  15. Remove the connectors and the wiring harness from the case.
  16.  
  17. Remove the 4 clips and 4 screws; remove the upper casing and then the lower casing.
  18.  
  19. Disconnect the liquid tube from the inlet fitting of the expansion tube.
  20.  
  21. Remove the packing and the heat sensing tube from the suction tube of the evaporator.
  22.  

Cap the open lines and fittings immediately to prevent the entry of dirt and moisture.

  1. Remove the expansion valve.
  2.  

To install:
  1. Inspect the evaporator fins for blockage. Check all the fittings for cracks or scratches. Never use water to clean the evaporator.
  2.  
  3. When reinstalling, assemble the expansion valve to the inlet fitting of the evaporator and tighten the nut to 17 ft. lbs.
  4.  
  5. Install the heat sensing tube and its packing to the suction tube of the evaporator.
  6.  
  7. Connect the liquid tube to the inlet fitting of the expansion valve and tighten it to 10 ft. lbs.
  8.  
  9. Assemble the lower casing and the upper casing and secure them with the 4 clips and the 4 screws.
  10.  
  11. Connect the wiring harness connectors.
  12.  
  13. Place the assembled unit in place within the car and secure its 4 mounting bolts and 4 nuts.
  14.  
  15. Install the wiring connectors onto the evaporator case.
  16.  
  17. Install the glove box.
  18.  
  19. Install the grommets on the inlet and outlet fittings.
  20.  
  21. Connect the liquid tube to the inlet fitting. Make sure the O-ring is in place and that the joint is correctly threaded. Tighten the joint to 10 ft. lbs. Do not overtighten.
  22.  
  23. Install the suction tube to the case inlet fitting. Make sure the O-ring is in place and that the joint is correctly threaded. Tighten the joint to 24 ft. lbs. Do not overtighten.
  24.  
  25. If the evaporator was replaced with a NEW unit, add 1.5 oz. of compressor oil to the compressor. This replaces oil in the system removed with the old evaporator.
  26.  
  27. Connect the negative battery cable.
  28.  
  29. Evacuate and recharge the air conditioning system.
  30.  



Click image to see an enlarged view

Fig. Fig. 3: Evaporator components - 1989-92

1991-92

See Figure 3

  1. Disconnect the negative battery cable. Discharge and recover the refrigerant from the system as outlined in Routine Maintenance .
  2.  
  3. Disconnect the outlet tube from the evaporator assembly, then disconnect the (inlet) liquid line from the assembly. Cap the open fittings immediately to prevent the entry of dirt and moisture.
  4.  
  5. Disconnect the hold-down brackets for both inlet and outlet lines.
  6.  
  7. Remove the right lower instrument panel trim assembly.
  8.  
  9. Disconnect the A/C amplifier electrical connector and remove the amplifier from the vehicle.
  10.  
  11. Remove the evaporator bolts and nuts from the evaporator case.
  12.  
  13. Disconnect the thermistor electrical connector.
  14.  
  15. Remove the evaporator case from the vehicle.
  16.  
  17. Separate the evaporator case halves.
  18.  
  19. Remove the A/C thermistor from the evaporator.
  20.  
  21. Remove the evaporator from the case.
  22.  
  23. Disconnect the expansion valve inlet pipe from the expansion valve and remove the expansion valve from the vehicle.
  24.  

To install:
  1. Install the expansion valve to the vehicle. Tighten the expansion valve to evaporator fitting to 24 ft. lbs. (32 Nm) and tighten the expansion valve inlet pipe to 17 ft. lbs. (23 Nm).
  2.  
  3. Install the evaporator into the lower evaporator case.
  4.  
  5. Install the A/C thermistor to the evaporator.
  6.  
  7. Combine the evaporator case halves.
  8.  
  9. Install the evaporator case into the vehicle and tighten the evaporator bolts and nuts to 11 ft. lbs. (15 Nm).
  10.  
  11. Install the amplifier to the vehicle and connect the A/C amplifier electrical connector
  12.  
  13. Install the A/C thermistor to the evaporator and connect the connector.
  14.  
  15. Install the right lower instrument panel trim assembly.
  16.  
  17. .Connect the outlet and the (inlet) liquid line to the evaporator and tighten both pipe fittings to 24 ft. lbs. (32 (Nm).
  18.  
  19. Connect the hold-down brackets for both inlet and outlet lines.
  20.  
  21. Evacuate and charge the A/C system as outlined in Routine Maintenance .
  22.  
  23. If the evaporator was replaced, add 1.4-1.7 oz. of compressor oil to the compressor. Connect the negative battery cable.
  24.  
  25. Operate the A/C system and check for leaks.
  26.  

1993

See Figure 4

  1. Disconnect the negative battery cable. Discharge and recover the refrigerant from the system as outlined in Routine Maintenance .
  2.  
  3. Remove the right side kick panel by removing the 1 plastic retaining nut.
  4.  
  5. Remove the glove box by removing the 3 nuts and 3 screws.
  6.  
  7. .Disconnect the outlet tube from the evaporator assembly, then disconnect the (inlet) liquid line from the assembly. Cap the open fittings immediately to prevent the entry of dirt and moisture.
  8.  
  9. Disconnect the hold-down brackets for both inlet and outlet lines.
  10.  
  11. Disconnect the A/C amplifier electrical connector and remove the amplifier from the vehicle.
  12.  
  13. Remove the evaporator bolts and nuts from the evaporator case.
  14.  
  15. Disconnect the thermistor electrical connector.
  16.  
  17. Remove the evaporator case from the vehicle.
  18.  
  19. Separate the evaporator case halves.
  20.  
  21. Remove the A/C thermistor from the evaporator.
  22.  
  23. Remove the evaporator from the case.
  24.  
  25. Disconnect the expansion valve inlet pipe from the expansion valve and remove the expansion valve from the vehicle.
  26.  

To install:
  1. Install the expansion valve to the vehicle. Tighten the expansion valve to evaporator fitting to 48 inch lbs. (5.4 Nm) and tighten the expansion valve inlet pipe to 48 inch lbs. (5.4 Nm).
  2.  
  3. Install the evaporator into the lower evaporator case.
  4.  
  5. Install the A/C thermistor to the evaporator.
  6.  
  7. Combine the evaporator case halves.
  8.  
  9. Install the evaporator case into the vehicle and tighten the evaporator bolts and nuts to 89 inch lbs. (10 Nm).
  10.  
  11. Install the amplifier to the vehicle and connect the A/C amplifier electrical connector
  12.  
  13. Install the A/C thermistor to the evaporator and connect the connector.
  14.  
  15. Connect the inlet line to the evaporator and tighten pipe fitting to 124 inch lbs. (14 Nm).
  16.  
  17. Connect the outlet line to the evaporator and tighten pipe fitting to 24 ft. lbs. (32 Nm).
  18.  
  19. Connect the hold-down brackets for both inlet and outlet lines.
  20.  
  21. Install the glove box and tighten the 3 nuts and 3 screws to 89 inch lbs. (10 Nm).
  22.  
  23. Install the right side kick panel and tighten the 1 plastic retaining nut to 89 inch lbs. (10 Nm).
  24.  
  25. Evacuate and charge the A/C system as outlined in Routine Maintenance .
  26.  
  27. If the evaporator was replaced, add 1.4-1.7 oz. of compressor oil to the compressor. Connect the negative battery cable.
  28.  
  29. Operate the A/C system and check for leaks.
  30.  



Click image to see an enlarged view

Fig. Fig. 4: Evaporator components - 1993

 
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