Heater Core

Complete heater core replacement for 2005 Dodge Viper requiring dashboard removal, HVAC housing disassembly, and coolant system service.

Warnings

Tools required

Parts

• Heater core × 1 — Use OEM specification
• Heater core tube O-rings × 2 — Use OEM specification
• HVAC housing foam seals × 1 — Use OEM specification
• Dashboard fastener clips (assorted) × 1 — Use OEM specification
• Coolant (Zerex G-05 HOAT 50/50) × 1 — 19 quart capacity

Fluids

• Zerex G-05 HOAT 50/50 — 19 qt

Preparation

1. Position vehicle on level surface in well-ventilated workspace with adequate overhead clearance for dashboard removal
2. Allow engine to cool completely (minimum 2 hours)
3. Have qualified technician recover AC refrigerant using certified R-134a recovery equipment
4. Disconnect negative battery cable and wait 2 minutes for airbag system capacitor discharge
5. Remove driver and passenger airbags per manufacturer safety procedures
6. Drain coolant from radiator petcock into appropriate container
7. Place protective covering over seats, center tunnel, and floor carpet
8. Remove both front seats by unbolting from floor tracks (4 bolts per seat, retain shims for reinstallation)
9. Photograph or label all electrical connections during disassembly

Procedure

1. 1

   Disconnect heater hoses at firewall
   Locate heater core inlet and outlet tubes penetrating firewall on passenger side of engine bay. Release spring clamps on both heater hoses using hose clamp pliers. Disconnect hoses from heater core tubes - expect residual coolant spillage. Cap or plug tubes and hoses to minimize coolant loss. Remove firewall grommet by pulling toward engine bay.
2. 2

   Remove steering column covers and lower dash panels
   Remove upper and lower steering column shrouds by releasing the snap clips at the rear of each shroud. Remove knee bolster panel below steering column by removing 4 Torx screws. Remove driver side lower dash panel by releasing panel clips and removing Torx fasteners along upper edge. Disconnect any electrical connectors from removed panels (courtesy lights, switches).
3. 3

   Disconnect steering column and remove from vehicle
   Disconnect steering shaft coupler bolt at firewall junction (mark orientation before removal). Disconnect all steering column electrical connectors (ignition switch, multifunction switch, clockspring). Remove 4 steering column mounting bracket bolts. Carefully lower and remove steering column assembly from vehicle - protect knee bolster area from contact damage.
4. 4

   Remove center console assembly
   Remove shifter boot and bezel by releasing from console. Remove center console side trim panels. Locate and remove all console mounting fasteners (combination of Torx screws at front, sides, and rear - typically 8-10 fasteners total). Disconnect electrical connectors for power accessories. Lift console up and rearward to clear shifter, then remove from vehicle.
5. 5

   Remove passenger side lower dash and glove box
   Remove passenger side lower dash panel by releasing clips and removing Torx fasteners. Open glove box and remove contents. Squeeze sides of glove box inward to release stop tabs and lower fully. Remove glove box mounting screws (typically 4 fasteners) and disconnect glove box lamp connector. Remove glove box assembly.
6. 6

   Disconnect dashboard electrical connections and HVAC controls
   Working from both driver and passenger sides, systematically disconnect all dashboard electrical connectors: instrument cluster, HVAC controls, radio/navigation, airbag control module, accessory switches, and door jamb harness connectors. Disconnect vacuum lines from HVAC mode control actuator. Disconnect antenna cable from radio. Label or photograph each connection for reinstallation reference.
7. 7

   Remove dashboard mounting fasteners and extract dashboard
   Locate all dashboard mounting points: 2 bolts at each A-pillar junction, 4 bolts along top edge at windshield base, 2-3 bolts at center support bracket, and 2 bolts at each end of dashboard. All fasteners are typically Torx head. Remove all dashboard mounting bolts systematically. With assistant support, carefully pull dashboard rearward to clear windshield studs and lift from vehicle. Dashboard is heavy and awkward - use care to avoid contact with door sills or windshield.
   ⚠Dashboard assembly weighs approximately 40-50 pounds and requires two people for safe removal. Avoid contact with windshield and painted surfaces.
8. 8

   Access and remove HVAC housing assembly
   With dashboard removed, HVAC housing is now fully accessible. Disconnect remaining electrical connectors from blower motor, blend door actuators, and mode door actuators on HVAC housing. Disconnect evaporator temperature sensor connector. Remove blower motor assembly (3 screws) for access. Locate HVAC housing mounting bolts (typically 6-8 bolts around perimeter of housing where it mounts to firewall and floor structure). Remove all housing mounting bolts.
9. 9

   Separate HVAC housing and extract from vehicle
   Carefully pull HVAC housing assembly away from firewall - heater core tubes and evaporator connections will separate as housing moves rearward. Maneuver housing out from under remaining structure, tilting as necessary to clear. Place housing on clean work surface. Expect residual coolant drainage from heater core passages.
10. 10

    Disassemble HVAC housing to access heater core
    Position HVAC housing with access door facing upward. Remove housing cover retaining screws around perimeter of housing (typically 10-12 screws). Carefully separate upper and lower housing halves - note position of foam seals and door linkages during separation. Remove blend door actuator linkage from heater core access door. Lift heater core from lower housing section - heater core is retained by tabs and mounting bracket.
11. 11

    Install new heater core and reassemble HVAC housing
    Inspect heater core mounting bracket and foam seals - replace if deteriorated. Install new O-rings on heater core tube connections (lubricate with coolant). Position new heater core in lower housing section, seating into mounting tabs. Reconnect blend door actuator linkage. Inspect all foam seals in housing mating surfaces and replace if compressed or damaged. Position upper housing half over lower half, aligning door shafts and ensuring all seals are properly positioned. Install housing cover screws in star pattern to ensure even sealing pressure.
12. 12

    Reinstall HVAC housing assembly to vehicle
    Maneuver HVAC housing back into position under firewall area, carefully aligning heater core tubes with firewall penetrations. Push housing firmly toward firewall to seat heater core tubes through firewall and engage evaporator connections. Install HVAC housing mounting bolts and tighten. Reinstall blower motor assembly (3 screws). Reconnect all electrical connectors to blower motor and actuators on HVAC housing.
13. 13

    Reinstall dashboard assembly
    With assistant, position dashboard assembly into vehicle, carefully aligning over steering column opening and windshield mounting studs. Guide dashboard forward until mounting holes align with body structure. Install all dashboard mounting bolts at A-pillars, center support, windshield base, and end caps. Tighten dashboard fasteners in sequence from center outward to ensure proper alignment. Reconnect all electrical connectors, vacuum lines, and antenna cable in reverse order of removal.
14. 14

    Reinstall steering column and interior components
    Position steering column into mounting bracket location and install 4 mounting bolts. Align steering shaft coupler to intermediate shaft (match marks made during removal) and install coupler bolt to specification. Reconnect all steering column electrical connectors. Install knee bolster panel and lower dash panels with Torx fasteners. Install steering column shrouds. Reinstall center console assembly with all mounting fasteners. Install glove box assembly and passenger lower dash panel. Reinstall both front seats with original mounting bolts and shims.
15. 15

    Connect heater hoses and refill coolant system
    Working in engine bay, install firewall grommet around heater core tubes. Connect heater hoses to heater core inlet and outlet tubes, positioning spring clamps in proper orientation. Ensure hoses are fully seated on tubes. Fill cooling system with Zerex G-05 HOAT 50/50 coolant through radiator fill point and overflow reservoir. Start engine and bring to operating temperature with heater on maximum heat setting. Monitor coolant level and add as necessary to purge air from system. Check for leaks at heater core connections.
16. 16

    Evacuate, recharge AC system, and perform final checks
    Have qualified technician evacuate AC system to verify no leaks, then recharge with proper R-134a refrigerant capacity per manufacturer specification. Reconnect negative battery cable. Verify operation of all dashboard functions: instrument cluster, HVAC controls (all modes and temperatures), radio, switches, and accessories. Verify heater produces hot air at all fan speeds. Check for coolant leaks at firewall heater connections. Verify no coolant odor in cabin. Test AC performance. Perform final walk-around inspection of interior for loose panels or forgotten fasteners.

Reassembly

1. Torque all fasteners per specification list - dashboard screws are low torque and easily over-tightened
2. Ensure all electrical connectors are fully seated and locked - partial connections will cause multiple fault codes
3. Verify steering column shaft coupler alignment marks match before tightening coupler bolt
4. Coolant system may require multiple heat cycles to fully purge air - recheck level after first drive cycle
5. AC system must be professionally evacuated and recharged - DIY recharge will not properly verify system integrity

Verification

• Start engine and verify heater produces hot air within 5 minutes of cold start - should reach maximum heat by thermostat opening
• Test all HVAC modes (defrost, floor, panel, bi-level) - airflow should redirect smoothly without binding
• Verify AC produces cold air and compressor cycles normally - pressure test if performance is suboptimal
• Check for coolant leaks at firewall heater connections and inside vehicle under carpet - coolant odor indicates leak
• Verify coolant level remains stable after multiple heat cycles - dropping level indicates air pocket or leak
• Test all dashboard functions including instrument cluster, radio, switches, and accessory power outlets
• Verify no airbag warning lights remain illuminated after battery reconnection
• Inspect under dashboard from driver and passenger sides for any disconnected connectors or loose panels

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