AC Evaporator

Complete removal and replacement of the AC evaporator core, requiring full dashboard disassembly, HVAC housing separation, and refrigerant system evacuation and recharge.

Warnings

Tools required

Parts

• AC evaporator core × 1 — Use OEM specification
• Evaporator inlet/outlet o-rings × 1 — Use OEM specification
• Evaporator expansion valve (if serviced separately) × 1 — Use OEM specification
• HVAC housing foam seals × 1 — Use OEM specification
• Receiver/drier or accumulator × 1 — Replace whenever system is opened
• PAG oil for AC compressor × 1 — Use OEM specification

Fluids

• ac_refrigerant

Preparation

1. Park vehicle on level surface and engage parking brake.
2. Disconnect negative battery cable and wait minimum 2 minutes for airbag system discharge.
3. Using certified AC recovery equipment, fully evacuate R-134a refrigerant from the system and record amount recovered for recharge reference.
4. Allow engine and AC system to cool completely if recently operated.
5. Remove both front seats to provide adequate working space for dashboard removal.
6. Photograph all electrical connections and harness routing throughout the dashboard area for reinstallation reference.

Procedure

1. 1

   Remove center console and lower trim panels
   Remove the center console by first removing the shift boot trim ring (the 2008 Viper is equipped with a Tremec T56 6-speed manual only). Locate and remove the console mounting fasteners (approximately 6-8 fasteners securing console to tunnel and floor). Disconnect any electrical connectors for power outlets or switches. Lift console rearward and out of cabin. Remove lower dash trim panels on both driver and passenger sides by releasing retaining clips and removing any visible fasteners.
2. 2

   Remove instrument cluster and steering column covers
   Remove upper and lower steering column covers by releasing retaining clips. Tilt steering column to lowest position. Remove instrument cluster bezel by carefully prying at clip locations. Remove instrument cluster mounting screws (typically 4 fasteners). Pull cluster forward, disconnect electrical connectors (electronic speedometer signal, no mechanical cable is used), and remove cluster from vehicle.
3. 3

   Disconnect steering column and pedal assembly
   Mark steering shaft position relative to steering gear for proper reinstallation alignment. Remove steering shaft coupler bolt at firewall junction. Disconnect all steering column electrical connectors (airbag, switches, ignition). Remove steering column mounting fasteners (typically 4 nuts/bolts at bracket). Support column and carefully withdraw it enough to provide dashboard clearance without fully removing from vehicle. Disconnect brake pedal pushrod from brake booster by removing retaining clip and sliding pushrod off pin.
4. 4

   Disconnect dashboard electrical connections and harnesses
   Working systematically from one side to the other, disconnect all electrical connectors attached to the dashboard assembly. This includes: HVAC control module, radio/navigation unit, airbag connectors, lighting connectors, switch connectors, and any body control module connections. Release harness retaining clips that secure wiring to the dashboard structure. Document each connection location.
5. 5

   Remove dashboard mounting fasteners and extract dashboard
   Locate all dashboard mounting points along the windshield cowl area, side pillars, and center tunnel. Remove dashboard mounting bolts and nuts (approximately 8-12 primary mounting points). With an assistant supporting the dashboard, carefully withdraw the entire dashboard assembly rearward and out through the driver door opening. Take extreme care to avoid contact with door jambs, seats, and windshield. Set dashboard on protected surface.
6. 6

   Disconnect evaporator refrigerant lines at firewall
   Locate the evaporator inlet and outlet lines at the firewall (engine compartment side). These will have bolt-on flange connections or spring-lock couplings. If flange type, remove the 2 bolts securing each line connection. If spring-lock type, use appropriate disconnect tool to release couplings. Cap all open refrigerant ports immediately with plugs to prevent moisture intrusion and contamination. Remove and discard all o-rings from connections.
7. 7

   Remove HVAC housing assembly from firewall
   From inside the cabin, locate the HVAC housing mounting fasteners securing the unit to the firewall and floor. Remove all mounting nuts/bolts (approximately 4-6 fasteners). Disconnect any remaining hoses (drain tube) and electrical connections to the housing (blower motor, actuators). Carefully maneuver the entire HVAC housing assembly out from under the dash area and remove from vehicle. The unit is bulky; work carefully to avoid damaging heater core tubes or surrounding components.
8. 8

   Separate HVAC housing halves
   Place the HVAC housing assembly on a clean workbench. Locate the housing retaining clips or screws that join the upper and lower housing halves (typically 8-12 clips/fasteners around the perimeter). Carefully release all clips or remove all fasteners. Gently separate the housing halves, taking care not to damage the foam seals or internal blend doors. Note the position and routing of any actuator linkages.
9. 9

   Remove evaporator core from housing
   With the housing opened, the evaporator core will be visible in its designated cavity. Carefully lift the evaporator core straight up and out of the lower housing section. Note the position of any mounting brackets, expansion valve location, and temperature sensor placement. If the expansion valve is integral to the evaporator, it will come out with the core; if separate, carefully disconnect it. Inspect the housing interior for debris, leaves, or biological growth and clean thoroughly.
10. 10

    Install new evaporator core
    Install new o-rings on the evaporator inlet and outlet tubes using a small amount of refrigerant oil for lubrication. If expansion valve is separate, install it to the new evaporator core with new o-ring. Position the new evaporator core into the lower HVAC housing cavity, ensuring proper seating and alignment with the housing tube pass-throughs. Verify that any temperature sensors or mounting clips are properly positioned.
11. 11

    Reassemble HVAC housing
    Inspect all foam seals between housing halves and replace any that are damaged or compressed. Apply new foam seals if provided with evaporator kit. Carefully align the upper and lower housing halves, ensuring that blend door linkages and actuator rods are properly positioned and not pinched. Secure the housing halves with all retaining clips or screws, working around the perimeter systematically to ensure even sealing.
12. 12

    Reinstall HVAC housing to vehicle
    Carefully maneuver the assembled HVAC housing back into position under the dash area, guiding the evaporator tubes through the firewall opening. Align the housing with its mounting points on the firewall and floor. Install all mounting fasteners and tighten securely. Reconnect the drain tube and all electrical connections to the blower motor and actuators. From the engine compartment, connect the evaporator inlet and outlet lines to the tubes protruding through the firewall using new o-rings lubricated with refrigerant oil. Secure with mounting bolts or spring-lock couplings.
13. 13

    Reinstall dashboard assembly
    With an assistant, carefully position the dashboard assembly into the cabin through the driver door opening. Guide the dashboard into position, aligning all mounting points with the firewall, side pillars, and center tunnel. Install all dashboard mounting bolts and nuts, tightening in a systematic pattern to ensure even seating. Reconnect all electrical connectors, referring to photos taken during disassembly. Secure all wiring harnesses with their original retaining clips.
14. 14

    Reinstall steering column, instrument cluster, and trim
    Reconnect the brake pedal pushrod to the brake booster and secure with retaining clip. Position the steering column back to its mounting location and install all mounting fasteners. Align the steering shaft with the marks made during removal and install the coupler bolt at the firewall junction. Reconnect all steering column electrical connectors. Install the instrument cluster, connecting speedometer cable and electrical connectors, then secure with mounting screws. Install instrument cluster bezel. Install steering column covers. Install all lower dash trim panels and center console, reconnecting any electrical connections.
15. 15

    Evacuate, leak test, and recharge AC system
    Reconnect the negative battery cable. Using certified AC service equipment, pull a vacuum on the system for minimum 30 minutes (45-60 minutes preferred). Monitor vacuum hold to verify system integrity; vacuum should hold steady for 10-15 minutes after pump shutoff. If vacuum holds, recharge the system with the correct amount of R-134a refrigerant (refer to underhood label or service manual for exact capacity). Add the appropriate amount and viscosity of PAG oil per the 2008 Viper FSM to compensate for oil retained in the removed evaporator (verify exact make-up amount and PAG grade against the service manual specification). Use leak detector to check all connections. Start engine, activate AC system, and verify proper operation of all modes and temperatures. Note: Verify AC system maintains proper pressure readings per the 2008 Viper service specification (confirm target low-side and high-side pressures against the FSM for the measured ambient temperature).

Reassembly

1. Reinstall front seats and torque mounting bolts to specification.
2. Verify all dashboard trim panels, vents, and bezels are fully seated and secure.
3. Test all dashboard functions including HVAC controls, radio, gauges, and lighting.
4. Verify proper operation of steering column functions including tilt, airbag light status, and all switch functions.

Verification

• Start engine and verify AC system engages compressor clutch without abnormal noise.
• Check that cold air is produced at all vents within 2-3 minutes of operation.
• Verify proper airflow distribution in all HVAC modes (defrost, panel, floor, mixed).
• Check for refrigerant leaks at evaporator line connections using leak detector.
• Verify no refrigerant odor in cabin during AC operation.
• Confirm proper temperature control throughout the range from full cold to full heat.
• Inspect cabin floor for signs of refrigerant oil or condensate leaks after 24 hours of operation.
• Verify AC system maintains proper pressure readings (typically 25-35 psi low side, 200-250 psi high side at idle with 90°F ambient).

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle