Rear Heater-A/C Housing Removal and Installation
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.
Quarter Trim Panel:

6. Remove right quarter trim panel and D-pillar trim. Refer to: "Body and Frame : Interior Trim : Trim Panel : Service and Repair" Service and Repair
Lower Heater Duct:

7. Remove screws securing air distribution duct to the rear wheel housing.
Heater Core Lines:

8. Pinch off heater lines at heater core hookup.
Heater Hoses:

9. Remove heater hoses at heater core.
Trim Panel Mounting Bracket:

10. Remove quarter trim panel mounting bracket.
11. Remove blower motor wiring harness connector.
Upper Duct Trim:

12. Remove rear upper duct trim screw.
Mounting Bolts:

13. Remove (2) Heater-A/C housing mounting bolts.
A/C Unit Replacement:

14. Pull up on upper A/C duct. Tilt A/C unit outward.
15. 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 O-rings at refrigerant lines. Evacuate and charge the refrigerant system. Fill the heater core. Test for leaks and overall performance.
NOTE: If 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 fill cap. Therefore the heater core will not gravity fill 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 filled 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 degree and 145 degree Fahrenheit.