Heater Core

Replace the heater core in a 2008 Dodge Viper, requiring extensive dashboard and HVAC housing disassembly to access the core located deep behind the center console.

Warnings

Tools required

Parts

• Heater core × 1 — Use OEM specification
• Heater core inlet/outlet O-rings or seals × 1 — Use OEM specification
• A/C expansion valve O-ring kit × 1 — Use OEM specification
• HVAC housing foam seal tape × 1 — Use OEM specification

Fluids

• Mopar HOAT coolant 50/50 — 19 qt
• R-134a

Preparation

1. Park vehicle on level surface and engage parking brake.
2. Disconnect negative battery cable and wait 10 minutes for airbag system capacitors to discharge.
3. Drain engine coolant completely by opening radiator petcock and removing radiator cap.
4. Have A/C system professionally recovered and evacuated.
5. Remove both front seats to provide working space (4 bolts per seat at base mounting points).
6. Remove center console completely including side trim panels and all mounting fasteners.
7. Prepare labeled bags or containers for organizing fasteners by location.

Procedure

1. 1

   Disconnect heater hoses in engine compartment
   Locate the heater core inlet and outlet hoses at the firewall on the passenger side of the engine compartment. Use hose clamp pliers to reposition the clamps, then carefully twist and pull the hoses from the heater core tubes. Allow any residual coolant to drain into a catch pan. Plug the heater core tubes with rubber caps or tape to prevent further coolant spillage during interior work.
2. 2

   Disconnect A/C lines at firewall
   Locate the A/C liquid line and suction line connections at the firewall near the heater hoses. Remove the bolt securing each line fitting (typically 10mm). Carefully separate the lines from the expansion valve or evaporator connections. Immediately cap all open A/C fittings to prevent moisture and debris contamination. Remove and discard the old O-rings from the line fittings.
3. 3

   Remove instrument panel upper cover
   Open the glove box and locate the fasteners along the upper edge of the instrument panel. Remove all visible screws securing the upper dash cover (look for Torx or Phillips fasteners at the windshield edge, A-pillar junctions, and above the gauge cluster). Gently release any clips along the front edge by prying with trim tools. Lift the upper cover away and disconnect any electrical connectors for gauge illumination or warning lights before fully removing.
4. 4

   Remove instrument cluster and gauge bezel
   Remove the fasteners securing the gauge cluster bezel (typically 4-6 Torx screws around the perimeter). Pull the bezel forward to access the instrument cluster mounting screws behind it. Remove the cluster mounting screws and pull the cluster partially forward. Disconnect the wiring harness connectors from the back of the cluster (typically 2-3 large multi-pin connectors). Remove the cluster completely and set aside in a safe location.
5. 5

   Disconnect steering column and remove knee bolster
   Lower the steering column to its lowest position. Remove the knee bolster panel below the steering column by removing the fasteners (check for hidden screws behind access covers). Remove the fasteners securing the steering column support bracket to the dashboard structure (typically 3-4 bolts). Disconnect the electrical connectors for the ignition switch, turn signal multifunction switch, and any other column-mounted components. Support the column and carefully lower it away from the dashboard, resting it on a protected surface.
6. 6

   Remove passenger airbag module
   From the glove box area, locate the passenger airbag mounting bolts accessible from behind (typically 4 bolts securing the airbag to the dashboard structure). Remove these bolts carefully. Pull the airbag module forward and disconnect the yellow airbag connector by releasing the locking tab. Remove the airbag and place it face-up in a secure location away from the work area where it will not be disturbed.
7. 7

   Remove glove box and lower dash panels
   Remove all fasteners securing the glove box assembly (check for screws inside the box, along the bottom edge, and at the hinge points). Disconnect any electrical connectors for glove box lighting. Remove the lower dash panels on both driver and passenger sides by locating and removing all fasteners and carefully releasing any remaining clips. These panels may be multi-piece assemblies with covered seams.
8. 8

   Disconnect dashboard wiring and controls
   Working systematically, disconnect all remaining electrical connectors attached to the dashboard structure including: HVAC control head, radio/navigation unit, hazard switch, power outlet connectors, ambient temperature sensor, and any other accessory wiring. Disconnect the vacuum line harness from the HVAC mode control vacuum actuators (typically a multi-port connector near the HVAC housing). Disconnect the heater control cables or servo connectors if equipped with automatic temperature control.
9. 9

   Remove dashboard mounting fasteners
   Locate and remove all dashboard mounting bolts securing the assembly to the cowl, A-pillars, and center support structure. Typical locations include: bolts at each A-pillar junction (2 per side), bolts along the top cowl edge (4-6 bolts), bolts at the center tunnel support (2-4 bolts), and bolts at the lower corners near the footwells (2 per side). Check carefully for any hidden fasteners before attempting to remove the dashboard.
10. 10

    Remove dashboard assembly
    With all fasteners and connections removed, carefully pull the dashboard assembly rearward. This requires two people due to the size and weight of the assembly. Guide the dashboard over the steering column support and any remaining obstructions. Once clear of the windshield and A-pillars, lift the dashboard up and out of the vehicle. Place it on a protected surface where it will not be damaged.
11. 11

    Remove HVAC housing fasteners
    With the dashboard removed, the HVAC housing is now visible mounted to the firewall. Remove all nuts and bolts securing the HVAC housing to the firewall and any support brackets (typically 6-10 fasteners total around the perimeter of the housing). Note the location of any ground straps or brackets that must be reinstalled. Disconnect any remaining vacuum lines or electrical connectors attached to actuators on the housing.
12. 12

    Remove HVAC housing from vehicle
    Carefully pull the HVAC housing assembly away from the firewall. The heater core tubes and evaporator connections pass through the firewall, so guide the housing carefully to avoid damaging the seals or grommets. Once clear of the firewall, maneuver the housing to remove it from the vehicle. The assembly is bulky but manageable with care.
13. 13

    Disassemble HVAC housing and remove heater core
    Place the HVAC housing on a clean work surface. Remove the screws or clips securing the housing halves together (typically 10-15 fasteners around the perimeter seam). Carefully separate the housing halves, noting the position of any foam seals, blend doors, and actuator linkages. Locate the heater core mounting bracket and remove the fasteners securing it (typically 2-3 screws or clips). Carefully slide the heater core out of its mounting position, being prepared for residual coolant drainage. Inspect the housing for any debris, leaves, or damage.
14. 14

    Install new heater core and reassemble housing
    Install new O-rings or seals on the heater core inlet and outlet tubes, lubricating them lightly with clean coolant. Carefully slide the new heater core into position in the HVAC housing, ensuring it seats properly in its mounting bracket. Secure the heater core bracket with its fasteners. Inspect all foam seals in the housing and replace any that are compressed or damaged. Carefully rejoin the housing halves, ensuring all blend door linkages are properly positioned and the seals are aligned. Install all housing fasteners and verify the housing is sealed completely.
15. 15

    Reinstall HVAC housing and dashboard
    Install the HVAC housing back into the vehicle, guiding the heater core tubes and evaporator connections through the firewall carefully. Install all housing mounting fasteners to the firewall and any support brackets. Reconnect all vacuum lines and electrical connections to actuators. Reinstall the dashboard assembly by reversing the removal process: position the dashboard over the cowl structure, install all mounting bolts at the A-pillars, cowl, center support, and lower corners. Reconnect all electrical connectors, control cables, and vacuum harnesses. Reinstall the steering column, instrument cluster, gauge bezel, airbag module, glove box, all trim panels, and the upper dash cover. Reinstall the center console and front seats.
16. 16

    Reconnect cooling system and A/C lines
    In the engine compartment, install new O-rings on the A/C line fittings, lubricating them with refrigerant oil. Connect the A/C lines to the firewall fittings and install the retaining bolts. Remove the plugs from the heater core tubes and reconnect the heater hoses, positioning new clamps properly. Reconnect the negative battery cable.
17. 17

    Refill cooling system and test
    Close the radiator petcock. Fill the cooling system with Mopar HOAT coolant 50/50 mixture (verify total capacity against factory service specification for the 2008 Viper 8.4L V10). Use a coolant funnel with adapter if available to help purge air from the system. Start the engine and allow it to reach operating temperature with the heater on maximum setting. Monitor coolant level and add as necessary while the system purges air. Check for leaks at the heater core connections. Once the thermostat opens and coolant circulates fully, verify hot air output from the heater vents.
18. 18

    Evacuate and recharge A/C system
    Have the A/C system professionally evacuated using a vacuum pump (minimum 30 minutes vacuum hold) to remove all moisture. Once vacuum test confirms no leaks, recharge the system with R-134a refrigerant to the proper capacity per the underhood specification label. Test A/C operation and verify cold air output from all vents.

Reassembly

1. Reassembly is covered in the procedure steps above, following reverse order of disassembly.
2. Ensure all electrical connectors are fully seated and locked.
3. Verify all dashboard fasteners are reinstalled and properly tightened.
4. Test all dashboard functions before final trim installation: gauges, switches, HVAC controls, airbag warning light operation.
5. Torque seat mounting bolts properly (not specified in database; use OEM specification).

Verification

• Start engine and verify no coolant leaks at heater core connections both inside vehicle and at firewall.
• Verify heater produces hot air at all temperature settings and fan speeds.
• Verify A/C produces cold air and cycles properly.
• Check that all HVAC modes function correctly (defrost, floor, panel, bi-level).
• Verify all dashboard functions operate properly: gauges, warning lights, switches, radio.
• Confirm airbag warning light performs normal bulb check and extinguishes, indicating proper airbag system function.
• Check coolant level after vehicle cools and top off if necessary.
• Inspect carpet and interior trim for any coolant staining; clean if necessary.

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