This procedure covers the removal and replacement of the heater core in a 2023 Rivian EDV 500, including coolant drainage, HVAC module access, and system refill.

Warnings

Tools required

Parts

• Heater core × 1 — Use OEM specification
• Heater core inlet/outlet o-rings × 2 — Use OEM specification
• HVAC module gasket/seal × 1 — Use OEM specification
• Coolant hose clamps × 2 — Use OEM specification

Fluids

• EV Battery/Motor Coolant — 10 qt

Preparation

1. Park vehicle on level surface and apply parking brake
2. Ensure vehicle has been off for at least 5 minutes to allow high-voltage system to discharge
3. Disconnect 12V battery negative terminal and wait 2 minutes for system capacitors to discharge
4. Place protective covering over front seats and floor carpet to prevent coolant damage
5. Connect Rivian diagnostic tool and place vehicle thermal management system into service mode
6. Position coolant drain pan under vehicle at front coolant drain locations
7. Allow coolant system to cool completely if vehicle was recently operated

Procedure

1. 1

   Drain coolant system
   Locate the coolant drain valve on the thermal management system located in the front underbody area. Open the drain valve and drain coolant into the drain pan. Remove the coolant reservoir cap to allow complete drainage. Drain approximately 2-3 quarts to reduce spillage during heater core removal.
2. 2

   Remove lower instrument panel covers
   Remove the lower dashboard trim panels on both driver and passenger sides using trim removal tools. Start at the bottom edges and work upward to release clips. Disconnect any electrical connectors for ambient lighting. Remove the center lower console trim piece accessing the HVAC ducting area.
3. 3

   Disconnect steering column and pedal assemblies
   Lower the steering column to its lowest position. Remove the steering column shroud covers. Disconnect the steering column electrical connectors and remove the steering column mounting bolts. Carefully lower and support the steering column without placing stress on the intermediate shaft. This provides access to the upper HVAC module area.
   ⚠Do not allow the steering column to hang unsupported as this may damage the intermediate steering shaft or electronic components.
4. 4

   Remove instrument panel center stack
   Remove the center touchscreen display by disconnecting its electrical connectors and removing mounting fasteners. Remove the center stack trim panel and HVAC control module. Disconnect all electrical connections to the HVAC controls, USB ports, and other center stack components. Set components aside in a safe location.
   ⚠The touchscreen display is fragile and expensive. Handle with care and place on a padded surface face-up.
5. 5

   Access heater core inlet/outlet connections
   From the engine compartment, locate the heater core inlet and outlet hoses at the firewall on the passenger side. Using hose clamp pliers, release the spring clamps securing the heater hoses. Place absorbent material below the connections as residual coolant will drain. Carefully disconnect both heater hoses from the firewall fittings.
   ℹ️Expect approximately 1 cup of coolant to drain from the hoses. Have shop towels ready.
6. 6

   Remove HVAC module fasteners
   From inside the vehicle, locate and remove all HVAC module mounting fasteners. These are typically located along the firewall interface and at the module-to-dash mounting points. There are usually 8-12 fasteners securing the HVAC module. Keep fasteners organized by location for reassembly.
7. 7

   Disconnect HVAC electrical connections
   Disconnect all electrical connectors from the HVAC module including the blower motor connector, temperature blend door actuator, mode door actuator, and any temperature sensors. Release all wiring harness routing clips securing harnesses to the HVAC module.
8. 8

   Remove HVAC module
   With an assistant, carefully pull the HVAC module rearward into the cabin to disengage it from the firewall and ducting connections. The module is bulky and requires maneuvering past the steering column support and center console structure. Once clear of all obstructions, remove the module from the vehicle and place on a clean work surface.
   ⚠The HVAC module is large and awkward to remove. Use caution to avoid damaging interior trim or electrical components during removal.
9. 9

   Disassemble HVAC module
   With the HVAC module on the workbench, remove the module case fasteners (typically screws or clips around the perimeter). Separate the case halves carefully. Note the orientation and position of all internal components including blend doors, actuators, and foam seals.
10. 10

    Remove old heater core
    Locate the heater core within the HVAC module housing. Remove any retaining brackets or clips securing the heater core. Carefully slide the heater core out of its housing, noting its orientation and any foam seals or gaskets. Inspect the housing for debris or residual coolant and clean as necessary.
11. 11

    Install new heater core
    Install new o-rings on the heater core inlet and outlet tubes, lubricating lightly with coolant. Position any foam seals or gaskets in their proper locations. Carefully slide the new heater core into the HVAC module housing, ensuring proper alignment with mounting brackets and coolant tube passages. Secure with retaining clips or brackets.
    ⚠Ensure the heater core is fully seated and properly oriented. Improper installation can cause coolant leaks or restricted airflow.
12. 12

    Reassemble HVAC module
    Install new HVAC module gasket if required. Carefully align the HVAC module case halves, ensuring all internal components, doors, and actuators are properly positioned. Install all case fasteners and tighten securely. Verify all blend doors and actuators move freely.
13. 13

    Reinstall HVAC module in vehicle
    With an assistant, carefully position the HVAC module into the vehicle, aligning it with the firewall opening and ducting connections. Push the module forward until it seats against the firewall. Install all HVAC module mounting fasteners. Reconnect all electrical connectors including blower motor, actuators, and sensors. Secure wiring harness routing clips.
14. 14

    Connect heater hoses
    From the engine compartment, connect the heater core inlet and outlet hoses to the firewall fittings. Ensure hoses are fully seated on the fittings. Install new spring clamps or hose clamps and position them properly. Verify connections are secure.
15. 15

    Refill and bleed coolant system
    Using the coolant refill funnel, add EV Battery/Motor Coolant to the system through the coolant reservoir. Fill to the proper level. Close the coolant drain valve. Using the diagnostic tool, activate the thermal management system pump to circulate coolant and purge air from the system. Monitor coolant level and add as necessary. Run the pump cycle several times until no air bubbles are visible and coolant level stabilizes. Verify the heater core connections are leak-free.
    ⚠Proper bleeding is critical. Air trapped in the system can cause inadequate heating and potential component damage.

Reassembly

1. Reinstall the center stack components including touchscreen display and trim panels in reverse order of removal
2. Reinstall the steering column, ensuring proper alignment and torque specifications are met
3. Reinstall all lower dashboard trim panels and reconnect ambient lighting connectors
4. Reconnect the 12V battery negative terminal
5. Remove protective covering from seats and carpet
6. Verify all interior trim panels are properly secured with no gaps or loose clips

Verification

• Using the Rivian diagnostic tool, clear any diagnostic trouble codes and exit service mode
• Start the vehicle and activate the climate control system to maximum heat
• Verify both driver and passenger sides produce hot air within 5 minutes
• Check all heater core connections at the firewall for coolant leaks
• Verify coolant level is at the proper level in the reservoir after system reaches operating temperature
• Test all HVAC functions including mode selection, temperature control, and fan speeds to ensure proper operation
• Verify no coolant odor in the cabin and no fogging on the windshield
• Check for proper operation of all center stack functions including touchscreen and HVAC controls
• Road test the vehicle and verify consistent heat output and no coolant loss

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