Rear Heater-A/C Unit Replacement and Service

NOTE: Special effort must be used to keep all R-134a system components moisture-free. Moisture in the oil is very difficult to remove and will cause a reliability problem with the compressor.

REMOVAL

WARNING: On vehicles equipped with rear a/c, the refrigerant system must be emptied before performing the following operation. The engine cooling system must also be relieved of all pressure.

1. Using a refrigerant recovery machine, remove refrigerant from the A/C system. Disconnect A/C plumbing from rear heater A/C unit. Refer to: "Testing and Inspection" Testing and Inspection
2. Hoist vehicle.

A/C Lines:

3. Remove A/C lines at lower floor pan flange.

A/C Mounting:

4. Remove (3) A/C unit floor mounting nuts.
5. Lower vehicle.

D-PANEL REMOVAL
1. Remove rear header trim cover.
2. Remove liftgate sill plate.
3. Remove second rear seat belt turning loop on long wheel base vehicle.
4. Remove bolt holding second rear seat belt, if equipped, anchor to quarter on short wheel base vehicle.
5. Remove quarter trim bolster on short wheel base vehicle.

Right Quarter Panel D-Pillar:

6. Remove screws holding trim panel to attaching bracket on short wheel base vehicle.

Rear Quarter D-Pillar:

7. Disengage hidden clips holding trim to D-pillar.
8. Separate D-pillar trim panel from D-pillar. Refer to: "Body and Frame : Interior Trim : Trim Panel : Service and Repair" Service and Repair
9. Disengage speaker wire connector if equipped.
10. Pass second rear seat belt, if equipped, through slot in trim panel on short wheel base vehicle.
11. Separate D-pillar trim from vehicle.

TRIM PANEL REMOVAL

CAUTION: Disconnect the negative cable clamp from battery post. Damage to accessory feed circuit can result.

1. Remove first rear seat.
2. Remove second rear seat, if equipped.
3. Remove sliding door sill trim panel.
4. Remove quarter trim bolster. Refer to: "Body and Frame : Interior Trim : Trim Panel : Service and Repair" Service and Repair
5. Remove C-pillar trim panel.
6. Remove D-pillar trim panel.
7. Remove first rear seat belt anchor.
8. Remove second rear seat belt anchor on long wheel base vehicle.
9. Remove screws holding quarter trim to quarter panel from bolster area.
10. Remove screws holding rear edge of quarter trim to attaching bracket.
11. Disengage hidden clips holding front of quarter trim to quarter panel rearward of sliding door opening.
12. Separate quarter trim from quarter panel.
13. Disengage wire connector from accessory power outlet, if equipped.
14. Pass second rear seat belt through slot in trim panel on long wheel base vehicle.
15. Pass first rear seat belt through slot in trim panel.
16. Separate quarter trim panel from vehicle.

UNIT REMOVAL

Lower Heater Duct:

1. Remove screws securing air distribution duct to the rear wheel housing.

Heater Core Lines:

2. Pinch off heater lines at heater core hookup.

Heater Hoses:

3. Remove heater hoses at heater core.

Trim Panel Mounting Bracket:

4. Remove quarter trim panel mounting bracket.
5. Remove blower motor wiring harness connector.

Upper Duct Trim:

6. Remove rear upper duct trim screw.

Rear Heat A/C Module Mounting:

Remove (2) Heater-A/C housing mounting bolts.

A/C Unit Replacement:

7. Pull up on upper A/C duct. Tilt A/C unit outward.
8. Lift the unit enough to clear floor pan. Remove unit from the vehicle.

INSTALLATION

Filling Heater Core:

For installation, reverse the above procedures. Install new 0-rings at refrigerant lines. Evacuate and charge the refrigerant system. Fill the heater core. Test for leaks and overall performance.

NOTE: It the heater core was emptied and was not prefilled, it is necessary to thermal cycle the vehicle TWICE. The heater core is positioned higher than the radiator till cap. Therefore the heater core will not gravity till to level. To thermal cycle the vehicle, it must be operated till the thermostat opens, then turned off and allowed to cool. In order to verify that the auxiliary unit is tilled completely, the following procedure can be used:
- Vehicle at room temperature.
- Engine is brought up to operating temperature.
- Front unit is OFF, temperature slides are at full HEAT position.
- Engine is at idle.
- With rear blower motor ON HIGH.
- Discharge air temperature, measured at the dual register located on the C-pillar base, is between 135° and 145° F.