AC Evaporator

Complete removal and replacement of the AC evaporator core, requiring disassembly of the evaporator housing and dashboard components.

Warnings

Tools required

Parts

• AC evaporator core × 1 — Use OEM specification
• Evaporator case gasket/seal kit × 1 — Use OEM specification
• AC expansion valve O-rings × 1 — Use OEM specification
• Receiver-drier × 1 — Replace when system is opened
• Refrigerant oil × 1 — Mineral oil for R12 systems
• R12 refrigerant or approved substitute × 1 — Per system capacity

Preparation

1. Park vehicle on level surface and set parking brake
2. Disconnect negative battery cable
3. Verify AC system refrigerant type before beginning recovery
4. Recover all refrigerant from AC system using approved recovery equipment
5. Allow engine to cool completely if recently operated
6. Protect interior carpeting and seats with drop cloths
7. Remove glove box door and assembly for access to evaporator housing

Procedure

1. 1

   Disconnect refrigerant lines at firewall
   Working from engine compartment, use flare nut wrenches to disconnect the evaporator inlet and outlet lines at the firewall connections. Cap or plug all open lines immediately to prevent moisture entry and contamination. Allow any residual oil to drain into a container and measure quantity for replacement during reassembly.
2. 2

   Remove heater control cables and wiring
   From inside the passenger compartment, disconnect the temperature blend door cable at the evaporator housing. Label and disconnect the blower motor electrical connector and any other wiring attached to the evaporator housing assembly. Note cable routing for reinstallation.
3. 3

   Disconnect blower motor resistor
   Locate the blower motor resistor block on the evaporator housing. Disconnect the electrical connector and remove the mounting screws securing the resistor to the housing. Remove the resistor assembly.
4. 4

   Remove evaporator housing mounting nuts
   Remove the nuts securing the evaporator housing to the firewall studs. These are typically accessed from inside the passenger compartment. On the Rebel Machine, there are usually four mounting nuts around the perimeter of the housing at the firewall interface.
5. 5

   Remove evaporator housing assembly
   Carefully lower and withdraw the complete evaporator housing from under the dashboard. This may require maneuvering around the transmission tunnel and steering column. Work slowly to avoid damaging the housing or interior trim. Place housing on clean work surface.
6. 6

   Separate evaporator housing halves
   Remove all screws and clips securing the upper and lower halves of the evaporator housing together. Carefully separate the housing halves, noting the orientation of internal baffles, doors, and seals. Take photos before disassembly if needed for reference.
7. 7

   Remove expansion valve from old evaporator
   Carefully remove the thermostatic expansion valve from the old evaporator core. Note the sensing bulb position and capillary tube routing. Inspect expansion valve screen for debris. If valve is functioning properly and not contaminated, it can be reused with new O-rings.
8. 8

   Clean evaporator housing
   Thoroughly clean both halves of the evaporator housing, removing all old gasket material, debris, and corrosion. Inspect the housing for cracks or damage. Clean all air passages and ensure blend door and vent doors move freely without binding.
9. 9

   Install expansion valve on new evaporator
   Install new O-rings on the expansion valve connections, lubricating lightly with refrigerant oil. Attach the expansion valve to the new evaporator core in the same orientation as original. Ensure sensing bulb contacts the evaporator outlet tube and is properly secured.
10. 10

    Position new evaporator in housing
    Add the specified amount of fresh refrigerant oil to the new evaporator core (typically 2-3 oz to replace what was drained). Install new foam seals around evaporator perimeter. Position the new evaporator core in the lower housing half, ensuring proper alignment with refrigerant line passages through the firewall.
11. 11

    Reassemble evaporator housing
    Apply new gasket or seal between housing halves. Carefully align upper and lower housing sections, ensuring internal doors and linkages are properly positioned. Install and tighten all housing screws and clips in a cross-pattern to ensure even seal compression.
12. 12

    Install evaporator housing in vehicle
    Maneuver the assembled evaporator housing back into position under the dashboard, aligning the refrigerant line tubes with the firewall passages. Install mounting nuts onto firewall studs and tighten securely. Ensure housing is properly seated against firewall seal.
13. 13

    Reconnect blower motor and controls
    Reinstall the blower motor resistor block and electrical connector. Reconnect all wiring to the blower motor and any other electrical connections. Reconnect and adjust the temperature control cable to ensure proper blend door operation through full range.
14. 14

    Connect refrigerant lines
    Install new O-rings on refrigerant line connections, lubricating lightly with refrigerant oil. Connect evaporator inlet and outlet lines at the firewall fittings using flare nut wrenches. Tighten connections firmly but avoid over-tightening aluminum fittings.
15. 15

    Install new receiver-drier and evacuate system
    Install new receiver-drier in the AC system. Connect vacuum pump to system service ports and evacuate to 29+ inches of mercury for minimum 30 minutes. Hold vacuum for 30 minutes after pump shutoff to verify no leaks. If vacuum holds, system is ready for recharge. Recharge system to original specification (typically 2.5-3.0 lbs R12 or equivalent).

Reassembly

1. Reinstall glove box assembly
2. Reconnect negative battery cable
3. Verify all interior trim pieces are properly secured
4. Check that temperature and mode control cables operate smoothly through full range
5. Ensure no tools or parts were left in passenger compartment

Verification

• Start engine and turn AC to maximum cooling with blower on high
• Verify cold air from all dashboard vents within 2-3 minutes
• Check for refrigerant leaks at all connection points using leak detector
• Monitor system pressures with manifold gauges to confirm proper operation (approximately 25-35 psi low side, 200-250 psi high side at idle)
• Verify evaporator drain tube is draining condensate properly after several minutes of operation
• Check blend door operation by switching between heat and cool modes
• Listen for unusual noises from evaporator housing or blower motor
• Verify no refrigerant odor in passenger compartment

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