Inverter Coolant Service

This procedure covers draining, flushing, and refilling the inverter coolant system on the 2024 Rivian EDV 500 dual motor AWD electric delivery van.

Warnings

Tools required

Parts

• Inverter coolant drain plug seal/washer × 2 — Use OEM specification
• Inverter coolant pump drain plug seal × 1 — Use OEM specification
• Coolant hose clamps (if damaged) × 4 — Use OEM specification

Fluids

• EV Battery/Motor Coolant — 10 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure high voltage system has been inactive for at least 30 minutes to allow coolant to cool
3. Verify coolant temperature is below 40°C (104°F) using diagnostic tool
4. Remove high voltage service disconnect located in rear cargo area per manufacturer procedure
5. Wait 5 minutes after disconnect removal for capacitor discharge
6. Verify zero voltage at inverter terminals using insulated multimeter rated for 1000V
7. Raise and support vehicle on jack stands at factory lift points
8. Remove belly pan and aerodynamic undertray to access inverter cooling system components
9. Place warning tags on service disconnect to prevent reconnection during service

Procedure

1. 1

   Access inverter cooling system
   Remove front wheel well liner on driver side to access front inverter coolant connections. Remove rear cargo floor panels to access rear inverter connections. Locate inverter coolant reservoir in front compartment near left frame rail.
2. 2

   Connect diagnostic tool and initiate coolant drain mode
   Connect Rivian diagnostic tool to vehicle OBD-II port. Navigate to Service Functions > Thermal Management > Inverter Coolant Service. Select 'Drain Mode' which will open all coolant valves and position actuators for complete drainage. This process takes approximately 2 minutes.
3. 3

   Drain front inverter coolant
   Position drain pan under front inverter assembly. Locate coolant drain plug on bottom of front inverter cooling plate. Remove drain plug slowly to allow pressure equalization. Allow coolant to drain completely (approximately 4-5 quarts). Inspect drain plug seal and replace if damaged or deformed.
4. 4

   Drain rear inverter coolant
   Reposition drain pan under rear inverter assembly accessed from cargo area. Remove rear inverter coolant drain plug. Allow coolant to drain completely (approximately 3-4 quarts). Check for metal particles or discoloration in drained coolant which may indicate component wear.
5. 5

   Drain coolant pump and reservoir
   Locate electric coolant pump mounted to front subframe. Remove pump drain plug and allow coolant to drain. Open coolant reservoir cap slowly to release any remaining pressure. Use coolant extraction pump or siphon to remove remaining coolant from reservoir.
6. 6

   Flush inverter cooling system
   Reinstall all drain plugs with new seals. Fill reservoir with fresh EV battery/motor coolant until half full. Using diagnostic tool, select 'Circulation Test' to run coolant pump for 30 seconds. Drain system again following steps 3-5. Repeat flush process until drained coolant appears clean and free of contaminants.
7. 7

   Inspect cooling system components
   With system drained, inspect all visible coolant hoses for cracks, swelling, or deterioration. Check hose clamps for corrosion or looseness. Inspect inverter housings for coolant leaks or staining. Verify coolant pump electrical connector is secure and free from corrosion. Replace any damaged components.
8. 8

   Install drain plugs and prepare for refill
   Install new sealing washers on all drain plugs. Torque drain plugs to specification per service manual (typically 20-25 Nm, but verify with manufacturer documentation as no torque specifications are provided in database). Ensure all coolant system connections are tight and properly seated.
9. 9

   Vacuum fill coolant system
   Connect coolant vacuum fill tool to coolant reservoir. Draw vacuum on system to -85 kPa (-25 inHg) minimum. Hold vacuum for 5 minutes and monitor for vacuum loss which indicates a leak. If vacuum holds, open fill valve and allow fresh EV coolant to be drawn into system. Fill until coolant reaches MAX mark on reservoir.
10. 10

    Initial coolant circulation and bleed
    Using diagnostic tool, select 'Initial Fill Circulation' which runs coolant pump at variable speeds for 10 minutes. Monitor coolant level and add coolant as needed. Check all drain plugs and connections for leaks. Coolant level will drop as system purges air.
11. 11

    Complete air purge cycle
    With diagnostic tool, run 'Air Purge Cycle' which cycles pump speed and operates inverter cooling valves through full range. This process takes approximately 15 minutes. Continue monitoring coolant level and top off as air is expelled. Observe for steady coolant flow without bubbles at reservoir.
12. 12

    Perform system pressure test
    Using diagnostic tool, select 'Pressure Test Mode' which pressurizes system to operating pressure. Inspect all connections, drain plugs, and hose joints for leaks. Allow system to hold pressure for 5 minutes. Any pressure loss indicates a leak that must be addressed.
13. 13

    Verify coolant concentration
    Extract coolant sample from reservoir using clean syringe. Test coolant concentration using refractometer or hydrometer. Verify coolant meets manufacturer specification (typically 50/50 premix EV coolant). Adjust concentration if necessary by adding concentrate or distilled water as needed.
14. 14

    Clear service mode and test system operation
    Exit all service functions in diagnostic tool. Reinstall high voltage service disconnect. Using diagnostic tool, clear any stored fault codes. Start vehicle and allow inverter cooling system to reach normal operating temperature. Monitor coolant temperature and flow using diagnostic tool. Verify system maintains proper temperature range (typically 40-65°C).

Reassembly

1. Reinstall all belly pans and aerodynamic undertrays removed during access
2. Reinstall wheel well liners and cargo floor panels
3. Verify coolant reservoir is at MAX level when system is cold
4. Torque all fasteners to specification
5. Remove all warning tags and tools from vehicle

Verification

• Using diagnostic tool, verify no active or pending fault codes related to inverter cooling system
• Confirm coolant level is stable at MAX mark with system cold
• Test drive vehicle and monitor inverter temperatures reach and maintain normal operating range
• Verify coolant pump operates normally through various drive modes and power demands
• Check for coolant leaks at all service points after test drive with system at operating temperature
• Document coolant service in vehicle maintenance records with date and coolant type used
• Verify inverter efficiency values are within normal range using diagnostic tool (typically 92-96% efficiency)

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