Battery Cooling System Service

Complete service of the battery thermal management cooling system including coolant drain, flush, component inspection, and refill with EV-specific coolant.

Warnings

Tools required

Parts

• Battery cooling system O-rings and seals kit × 1 — Use OEM specification
• Coolant filter element (if equipped) × 1 — Use OEM specification
• Underbody panel fasteners × 1 — Replace as needed

Fluids

• EV Battery/Motor Coolant — 10 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow battery and cooling system to cool for minimum 3 hours after last use or charging
3. Ensure 12V battery is fully charged (required for diagnostic procedures)
4. Connect Rivian diagnostic tool and verify no active high voltage faults
5. Document any existing fault codes related to thermal management system
6. Perform high voltage isolation lockout procedure per manufacturer protocol
7. Verify high voltage system is de-energized using insulated multimeter
8. Remove underbody panels to access battery pack cooling connections
9. Place coolant drain pan under battery pack drain location

Procedure

1. 1

   Disable High Voltage System
   Using the Rivian diagnostic tool, initiate service mode to disable high voltage contactors. Remove high voltage service disconnect located in rear cargo area beneath access panel. Install service plug lockout device. Measure voltage at battery terminals to confirm 0V. Wait minimum 10 minutes for capacitor discharge. Attach high voltage warning tags to service disconnect location.
2. 2

   Access Battery Cooling System
   Remove underbody protective panels securing battery pack access. Locate battery cooling system drain valve on driver side of battery enclosure. Identify coolant inlet and outlet ports, pump location, and chiller unit connections. Inspect visible cooling lines for damage, corrosion, or leakage. Photograph all connections for reassembly reference.
3. 3

   Drain Battery Coolant
   Position drain pan beneath battery pack drain valve. Open drain valve slowly to prevent splashing. Allow coolant to drain completely, which may take 15-20 minutes. Collect drained coolant in appropriate container for disposal or testing. Inspect drained coolant for contamination, discoloration, or debris. Check coolant with refractometer if available to assess condition.
4. 4

   Disconnect Cooling System Hoses
   Label all cooling system hose connections with their positions. Disconnect quick-connect fittings at battery pack inlet and outlet by depressing locking tabs while pulling hose away. Disconnect connections at battery chiller unit and coolant pump. Remove and inspect all O-rings and seals for wear, cracking, or deformation. Cap open ports to prevent contamination.
5. 5

   Remove and Inspect Coolant Pump
   Disconnect electrical connector from battery coolant pump. Remove mounting bolts securing pump to battery enclosure. Carefully extract pump assembly, noting orientation and any alignment pins. Inspect pump housing for cracks or damage. Check impeller for corrosion or debris buildup. Test pump motor resistance according to manufacturer specifications using multimeter.
6. 6

   Inspect and Service Coolant Filter
   Locate coolant filter housing on battery cooling circuit. Remove filter housing cover and extract filter element. Inspect filter for debris accumulation which indicates system contamination. If filter shows excessive debris, additional system flushing is required. Install new filter element with fresh O-ring seals. Clean filter housing before reassembly.
7. 7

   Inspect Battery Cooling Passages
   Using inspection mirror and flashlight, visually inspect accessible battery cooling passages within pack enclosure. Look for blockages, corrosion, or coolant residue indicating leaks. Check chiller unit heat exchanger fins for damage or debris. Inspect all visible cooling plates and thermal interface connections. Document any abnormalities for further investigation.
8. 8

   Flush Cooling System
   Connect coolant flushing equipment to battery cooling system inlet and outlet ports. Use only EV-specific coolant or deionized water for flushing (never tap water). Flush system until discharge runs clear with no debris. Ensure all old coolant is completely evacuated. Allow system to drain completely after flushing. Blow out residual fluid using filtered compressed air at low pressure (20-30 psi maximum).
9. 9

   Reinstall Coolant Pump
   Install new O-ring seals on coolant pump mounting surface, lubricating lightly with fresh EV coolant. Position pump in correct orientation, aligning any dowel pins or locating features. Install and hand-tighten mounting bolts, then torque in cross-pattern to specification. Reconnect electrical connector and verify secure latch. Check that pump rotates freely by hand if accessible.
10. 10

    Reconnect Cooling Hoses
    Install new O-rings on all quick-connect fittings, lubricating with fresh EV coolant. Reconnect cooling hoses to battery pack inlet and outlet ports, ensuring full insertion until click is heard or felt. Connect hoses to chiller unit and pump locations per reference photos. Tug on each connection to verify secure engagement. Ensure no hoses are kinked, pinched, or stretched.
11. 11

    Vacuum Fill Cooling System
    Connect coolant vacuum fill tool to battery cooling system fill port. Draw vacuum on system to minimum 25 inches Hg. Hold vacuum for 5 minutes and monitor for decay indicating leaks. If vacuum holds, introduce manufacturer-specified EV Battery/Motor Coolant through fill tool. Fill until fluid level reaches specified mark or until 10 quarts have been added. Close fill port and disconnect vacuum tool.
12. 12

    Bleed Cooling System
    Using Rivian diagnostic tool, initiate battery cooling system bleed procedure. This activates coolant pump in controlled sequence to purge air from system. Monitor coolant reservoir level and add fluid as needed during bleed process. Continue bleed procedure until no air bubbles are visible in reservoir and coolant level stabilizes. Top off coolant to maximum level mark.
13. 13

    Pressure Test System
    Connect cooling system pressure tester to fill port. Pressurize system to manufacturer-specified test pressure (typically 15-20 psi). Hold pressure for 10 minutes and monitor gauge for decay. Inspect all connections, hoses, and components for signs of leakage while under pressure. Address any leaks found before proceeding. Release pressure and remove test equipment.
14. 14

    Restore High Voltage System
    Remove high voltage warning tags and service plug lockout device. Reinstall high voltage service disconnect, ensuring secure engagement. Using diagnostic tool, exit service mode and re-enable high voltage system. Verify proper high voltage system initialization and monitor for fault codes. Confirm battery management system recognizes cooling system as operational.
15. 15

    System Verification and Testing
    Using diagnostic tool, monitor battery cooling system parameters including coolant temperature, pump speed, and flow rate. Command pump to various speeds and verify proper response. Check for leaks at all connections with system at operating temperature. Verify coolant temperature sensors are reading accurately. Perform thermal management system self-test through diagnostic software. Document all system parameters and confirm operation within normal ranges.

Reassembly

1. Reinstall all underbody protective panels using new fasteners where specified
2. Ensure all panel fasteners are properly seated and torqued
3. Verify no tools or materials were left in battery compartment area
4. Clean any spilled coolant from underbody and surrounding components
5. Reset service intervals in diagnostic tool if applicable

Verification

• Confirm no active fault codes related to battery thermal management system
• Verify coolant level is at maximum mark with system at operating temperature
• Monitor battery temperatures during charging cycle to ensure proper cooling function
• Confirm coolant pump operates smoothly without unusual noise or vibration
• Check that battery thermal management activates appropriately during fast charging
• Verify no coolant leaks present after 24-hour settling period
• Test drive vehicle and monitor battery temperatures remain within normal operating range
• Confirm cooling system maintains battery temperature within 20-40°C during normal operation

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