Cabin Heater - PTC

This procedure covers the removal and replacement of the PTC (Positive Temperature Coefficient) cabin heater assembly on the 2022 Rivian EDV 500 electric delivery van.

Warnings

Tools required

Parts

• PTC cabin heater assembly × 1 — Use OEM specification
• High-voltage connector seals × 2 — Use OEM specification
• Coolant hose clamps × 4 — Use OEM specification
• Heater assembly mounting gasket × 1 — 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 powered off for minimum 2 hours to allow coolant system to cool
3. Disconnect 12V auxiliary battery using 10mm wrench on negative terminal
4. Access high-voltage service disconnect located under front cargo area floor panel
5. Remove high-voltage service disconnect plug and store in secure location away from vehicle
6. Install high-voltage safety lock-out tag on service disconnect location
7. Wait minimum 10 minutes for high-voltage system capacitor discharge
8. Don high-voltage insulated gloves and place safety mat under work area
9. Verify zero voltage at multiple high-voltage connection points using multimeter

Procedure

1. 1

   Access cabin heater compartment
   Remove front lower dash panel below steering column using T20 Torx driver. Remove four Torx screws and carefully pull panel away from dash, disconnecting any electrical connectors for foot lighting. Remove driver side lower trim panel to expose heater core housing area on driver side firewall.
2. 2

   Drain coolant from heating circuit
   Locate coolant drain valve on heater inlet line near firewall penetration. Place drain pan beneath vehicle under heater area. Open drain valve using 10mm socket and drain approximately 1.5-2 quarts of EV coolant into collection pan. Coolant will be orange in color. Keep coolant clean for potential reuse if not contaminated.
3. 3

   Disconnect low-voltage control harness
   Locate the low-voltage control connector on the side of PTC heater assembly (gray 12-pin connector). Press release tab and pull connector straight out from heater body. Secure connector away from work area to prevent damage.
4. 4

   Verify high-voltage isolation
   Using high-voltage capable multimeter, verify zero voltage between both high-voltage terminals on PTC heater and vehicle ground. Test between positive and negative terminals as well. Record readings in service documentation. Do not proceed if any voltage is detected - re-verify service disconnect removal and wait additional time.
5. 5

   Disconnect high-voltage power cables
   While wearing high-voltage insulated gloves, locate orange high-voltage cables connected to PTC heater (typically two connections on top of unit). Use 13mm socket to loosen cable retention bolts. Carefully pull cables straight out from heater terminals. Inspect cable terminals and seals for damage. Cover exposed high-voltage terminals with insulating caps immediately after removal.
6. 6

   Remove coolant hoses
   Locate coolant inlet and outlet hoses connected to PTC heater (typically 5/8 inch diameter hoses on bottom of unit). Use hose clamp pliers or 7mm socket to loosen spring clamps or screw clamps. Twist hoses gently to break seal, then pull off heater barb connections. Have towels ready as residual coolant will drain. Plug hoses with rubber caps to prevent additional coolant loss.
7. 7

   Remove heater mounting fasteners
   Locate PTC heater assembly mounting bolts, typically four bolts securing unit to HVAC housing and firewall bracket. Remove bolts using 10mm socket. Support heater unit weight while removing final bolts to prevent dropping.
8. 8

   Extract PTC heater assembly
   Carefully maneuver PTC heater assembly out of mounting location, navigating around HVAC ducting and wiring harnesses. The unit measures approximately 10x8x6 inches. Angle assembly as needed to clear obstructions. Have second person assist with supporting weight during removal. Once clear, place old heater on bench for comparison with replacement unit.
9. 9

   Prepare new PTC heater
   Unpack new PTC heater assembly and compare with removed unit to verify correct replacement part. Transfer any brackets or mounting hardware from old unit if not included with new heater. Install new mounting gasket on heater mounting flange. Inspect new unit high-voltage terminals and apply dielectric compound to terminal surfaces if specified by manufacturer.
10. 10

    Install new PTC heater assembly
    Carefully maneuver new PTC heater into mounting location, reversing removal path. Align mounting holes with HVAC housing and firewall bracket. Start all four mounting bolts by hand before tightening. Tighten mounting bolts in cross pattern to ensure even seating. Verify heater sits flush against mounting surface.
11. 11

    Connect coolant hoses
    Install coolant inlet and outlet hoses onto heater barb connections. Inlet hose typically connects to lower left port, outlet to lower right port (verify with service diagram). Push hoses fully onto barbs until seated against barb shoulder. Install new hose clamps and position clamp 1/4 inch from hose end. Tighten clamps securely but avoid overtightening which can damage hoses.
12. 12

    Reconnect high-voltage cables
    Remove insulating caps from high-voltage cable terminals. While wearing high-voltage gloves, align cable terminals with heater high-voltage connections, ensuring correct polarity (positive marked with red/orange, negative marked with black/blue). Push terminals fully onto heater posts. Install and tighten retention bolts using 13mm socket. Ensure new high-voltage connector seals are properly seated. Do not overtighten as this can damage terminals.
13. 13

    Reconnect control harness
    Connect low-voltage control harness 12-pin gray connector to PTC heater. Push connector in until release tab clicks into locked position. Verify connector is fully seated by gently pulling on connector body.
14. 14

    Refill coolant system
    Close coolant drain valve on heater circuit. Using coolant funnel or vacuum fill tool at coolant reservoir, add EV Battery/Motor Coolant to bring system back to proper level. If using vacuum fill method, follow tool manufacturer instructions for complete air purge. Otherwise, add coolant slowly and allow air to burp from system. Run climate control system in heat mode after reinstallation to circulate coolant and check for proper fill level.
15. 15

    Reinstall interior panels
    Reinstall driver side lower trim panel and secure all clips. Reconnect any electrical connectors for foot lighting. Reinstall front lower dash panel below steering column and secure with four T20 Torx screws. Verify all panels are properly seated and all fasteners are tight.

Reassembly

1. Reconnect 12V auxiliary battery negative terminal and tighten to secure connection
2. Reinstall high-voltage service disconnect plug ensuring proper engagement and locking
3. Remove high-voltage safety lock-out tag
4. Verify coolant level is between MIN and MAX marks on reservoir when system is cold
5. Check under vehicle and in cabin for any coolant leaks

Verification

• Power on vehicle and verify no high-voltage system fault codes are present in instrument cluster
• Using diagnostic scan tool, verify PTC heater control module communication is active with no DTCs stored
• Set climate control to maximum heat (85°F/29°C) and high fan speed
• Allow heater to operate for 5 minutes and verify warm air is being produced at HVAC vents
• Monitor coolant temperature using scan tool - PTC heater should show active heating when cabin heat is demanded
• Verify coolant level remains stable after 10 minutes of heater operation with no visible leaks
• Check high-voltage connections at PTC heater for any signs of arcing, discoloration, or heat damage
• Test heater operation at various temperature settings to ensure full range of functionality
• Perform test drive and verify cabin heating performance meets normal operating expectations

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