Cabin Heater - PTC

This procedure covers the removal and replacement of the PTC (Positive Temperature Coefficient) cabin heater assembly on the 2024 Rivian EDV 500 electric delivery van.

Warnings

Tools required

Parts

• PTC cabin heater assembly × 1 — Use OEM specification
• HV connector seal kit × 1 — Use OEM specification
• Coolant hose clamps × 4 — Use OEM specification
• HVAC coolant O-rings × 2 — Use OEM specification

Fluids

• EV Battery/Motor Coolant — 2 qt

Preparation

1. Park vehicle on level surface and apply parking brake
2. Ensure vehicle has been shut down for at least 2 hours to allow coolant system to cool
3. Disconnect 12V auxiliary battery negative terminal and wait 10 minutes
4. Access the HV service disconnect located in the HV battery compartment per manufacturer procedures
5. Remove HV service disconnect and install lockout device
6. Wait minimum 5 minutes for HV capacitors to discharge
7. Put on high voltage safety gloves and use insulated tools
8. Verify HV system is de-energized using multimeter at multiple test points per service manual
9. Place warning tags on steering wheel indicating HV system is disabled
10. Remove lower HVAC access panel below dashboard on passenger side
11. Position coolant drain pan beneath vehicle under HVAC unit drain location

Procedure

1. 1

   Drain HVAC coolant circuit
   Locate the HVAC coolant drain valve on the lower front of the PTC heater assembly. Attach drain hose to valve and route to drain pan. Open drain valve and allow coolant to drain completely from the HVAC circuit. Close drain valve when flow stops.
2. 2

   Disconnect coolant lines
   Using hose clamp pliers, remove the spring clamps from the inlet and outlet coolant hoses at the PTC heater connections. Carefully disconnect both coolant hoses from the heater assembly. Have shop towels ready to catch residual coolant. Cap or plug the hose ends to prevent contamination.
3. 3

   Verify high voltage isolation
   Double-check that HV service disconnect is removed and locked out. Using HV-rated multimeter, verify zero voltage at the PTC heater HV connector terminals. Measure between both HV+ and HV- terminals and chassis ground. All readings must be 0V DC before proceeding.
4. 4

   Disconnect high voltage connector
   Release the orange safety lock on the HV connector by sliding it fully outward. Press the connector release tab and carefully pull the HV connector straight out from the PTC heater assembly. Inspect connector pins and seals for damage or corrosion. Cover the disconnected HV connector with insulating cap.
5. 5

   Disconnect low voltage connector
   Locate the 12V control connector on the side of the PTC heater assembly. Press the connector release tab and disconnect the control harness connector. Secure the harness away from the work area.
6. 6

   Remove temperature sensor
   Disconnect the coolant temperature sensor connector from the PTC heater housing. Using a 19mm wrench, carefully remove the temperature sensor from the heater assembly. Inspect the sensor O-ring and replace if damaged.
7. 7

   Remove PTC heater mounting fasteners
   Locate the four mounting bolts securing the PTC heater assembly to the HVAC module bracket. Using appropriate socket (typically 10mm), remove all four mounting bolts. Support the heater assembly with one hand while removing the final bolt.
8. 8

   Remove PTC heater assembly
   Carefully maneuver the PTC heater assembly out of the HVAC housing. Note the orientation and routing of any remaining attached components. The unit is heavy (approximately 25 lbs), so ensure proper support during removal. Set the old unit aside on a clean work surface.
9. 9

   Prepare new PTC heater
   Unpack the new PTC heater assembly and verify it matches the old unit. Install new O-rings on the coolant inlet and outlet ports using EV coolant as lubricant. Install new seals in the HV connector if provided in the seal kit. Verify all ports are clean and free of debris.
10. 10

    Install new PTC heater assembly
    Position the new PTC heater assembly into the HVAC housing, ensuring proper orientation matches the original installation. Align the mounting holes with the bracket. Install all four mounting bolts and tighten in a cross pattern to ensure even seating. Final tighten all bolts securely.
11. 11

    Reinstall temperature sensor
    Apply a thin layer of EV coolant to the new temperature sensor O-ring. Thread the sensor into the PTC heater housing by hand, then tighten with 19mm wrench until snug. Do not overtighten. Reconnect the sensor electrical connector.
12. 12

    Reconnect electrical connectors
    Connect the 12V control harness connector to the PTC heater, ensuring it clicks fully into place. Remove the insulating cap from the HV connector. Carefully align and insert the HV connector straight into the PTC heater assembly until fully seated. Slide the orange safety lock fully into the locked position. Tug gently on connector to verify secure engagement.
13. 13

    Reconnect coolant lines
    Remove the caps from the coolant hoses. Clean the coolant port connections on the new PTC heater. Connect the inlet and outlet coolant hoses to the appropriate ports on the heater assembly, ensuring hoses are fully seated. Install new spring clamps on both connections and verify they are properly seated in the hose grooves.
14. 14

    Refill and bleed coolant system
    Using vacuum fill tool if available, refill the HVAC coolant circuit with fresh EV Battery/Motor Coolant through the fill port. Fill to the proper level. If vacuum fill tool is not available, fill slowly and run the coolant pump in purge mode using diagnostic software to bleed air from the system. Top off coolant as needed until system is full and no air bubbles are present.
15. 15

    Restore vehicle to service
    Reinstall the lower HVAC access panel. Reconnect the 12V auxiliary battery negative terminal. Remove lockout device and reinstall the HV service disconnect per manufacturer procedures. Remove warning tags. Using Rivian diagnostic software, clear any stored fault codes and perform PTC heater functional test to verify proper operation.

Reassembly

1. Ensure all coolant connections are secure and no leaks are present
2. Verify all electrical connectors are fully engaged with safety locks in place
3. Confirm HV service disconnect is properly reinstalled and secured
4. Double-check that all tools and equipment have been removed from the vehicle

Verification

• Connect Rivian diagnostic software and verify no high voltage isolation faults are present
• Start vehicle and monitor coolant temperature rise on scan tool
• Set HVAC system to maximum heat and verify hot air output within 2-3 minutes
• Check for coolant leaks around all connections at the PTC heater assembly
• Verify coolant level is at proper mark after system has reached operating temperature
• Confirm PTC heater current draw is within specifications using diagnostic software (typically 5-7 kW at full output)
• Test all HVAC temperature settings and fan speeds to ensure proper operation

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