Heat Pump System

This procedure covers the removal and replacement of the heat pump system on the 2023 Chevrolet Bolt EUV, including disconnecting refrigerant lines, electrical connectors, and coolant connections.

Warnings

Tools required

Parts

• Heat pump assembly × 1 — Use OEM specification
• Refrigerant line O-rings × 4 — Use OEM R-1234yf compatible
• Coolant hose clamps × 2 — Use OEM specification
• Heat pump mounting grommets × 4 — Use OEM specification
• R-1234yf refrigerant × 1 — Use OEM specification

Fluids

• ACDelco DEX-COOL (Orange) — 1.5 qt

Preparation

1. Park vehicle on level surface and apply parking brake. Place wheel chocks at rear wheels.
2. Disconnect 12V battery negative terminal and wait 2 minutes for system capacitor discharge.
3. Follow GM high-voltage safety procedures: Remove HV service disconnect located under rear seat, verify HV disabled with multimeter.
4. Recover all R-1234yf refrigerant from the system using certified recovery equipment.
5. Drain approximately 1.5 quarts of coolant from heat pump circuit into drain pan by accessing drain valve on front coolant reservoir.
6. Raise and support front of vehicle on jack stands at recommended lift points.
7. Remove front passenger side wheel and inner fender liner to access heat pump assembly.
8. Remove lower belly pan fasteners and lower belly pan for access to heat pump mounting area.

Procedure

1. 1

   Remove front fascia cover
   Remove the front fascia lower cover to access refrigerant lines and electrical connections. Remove cover screws along bottom edge and release retaining clips. Support cover and disconnect any attached wiring for fog lights or sensors before fully removing.
   Torque spec

   Cover Screws11 Nm (8 lb-ft)
2. 2

   Disconnect refrigerant lines
   Locate the four refrigerant line connections at the heat pump assembly (two on compressor side, two on condenser/evaporator side). Use refrigerant line disconnect tools to release quick-connect fittings. Cap all open connections immediately to prevent moisture intrusion. Remove and discard all refrigerant line O-rings.
   ⚠Verify refrigerant has been fully recovered before disconnecting lines. Any remaining pressure indicates incomplete recovery.
3. 3

   Disconnect coolant lines
   Identify the two coolant lines connecting to the heat pump assembly. Place drain pan beneath connections. Release coolant line fittings using appropriate disconnect tool. Allow residual coolant to drain completely. Remove hose clamps if present.
   Torque spec

   Coolant Line Fittings15 Nm (11 lb-ft)

   Hose Clamps3 Nm (2 lb-ft)
4. 4

   Disconnect electrical connectors
   Locate all electrical connectors on the heat pump assembly: main power connector, temperature sensors (2), pressure sensors (2), and compressor control connector. Depress locking tabs and carefully disconnect each connector. Note routing and positions for reinstallation.
   Torque spec

   Connector Bolts7 Nm (5 lb-ft)

   Sensor Bolts11 Nm (8 lb-ft)
5. 5

   Remove support bracket
   Remove the heat pump support bracket bolts securing the assembly to the vehicle frame. There are typically 3 bracket bolts. Support the heat pump weight while removing the final bolts to prevent assembly from dropping.
   Torque spec

   Bracket Bolts20 Nm (15 lb-ft)
6. 6

   Remove heat pump mounting bolts
   Locate the four main mounting bolts securing the heat pump assembly to the vehicle subframe. Support the heat pump assembly with a suitable jack or support stand. Remove all four mounting bolts while supporting the assembly weight.
   ⚠Heat pump assembly weighs approximately 35 lbs. Use proper lifting technique and support equipment.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
7. 7

   Remove heat pump assembly
   Carefully lower the heat pump assembly from the vehicle, ensuring all electrical connectors, refrigerant lines, and coolant lines are fully disconnected. Maneuver assembly past surrounding components and remove from underneath vehicle. Inspect mounting grommets and replace if worn or damaged.
   ℹ️Check for any additional wiring harness routing clips or brackets that may still be attached before fully removing assembly.
8. 8

   Prepare new heat pump assembly
   Remove shipping caps from new heat pump assembly refrigerant ports. Install new O-rings on all refrigerant line connections, lubricating with clean refrigerant oil. Verify all sensor ports are properly sealed. Install new mounting grommets in all four mounting locations.
   ℹ️Do not remove refrigerant port caps until immediately before connection to minimize moisture exposure.
9. 9

   Install heat pump assembly
   Position new heat pump assembly into mounting location from underneath vehicle. Align mounting holes with subframe. Install all four mounting bolts finger-tight initially. Once all bolts are started, torque to specification in a cross pattern.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
10. 10

    Install support bracket
    Position heat pump support bracket and install bracket bolts. Torque bracket bolts to specification. Verify assembly is secure and properly aligned before proceeding.
    Torque spec

    Bracket Bolts20 Nm (15 lb-ft)
11. 11

    Reconnect electrical connectors
    Reconnect all electrical connectors in reverse order of removal: compressor control connector, pressure sensors, temperature sensors, and main power connector. Ensure all connectors are fully seated and locking tabs engage. Secure any harness routing clips. Torque sensor mounting bolts and connector bolts to specification.
    Torque spec

    Connector Bolts7 Nm (5 lb-ft)

    Sensor Bolts11 Nm (8 lb-ft)
12. 12

    Reconnect coolant lines
    Connect coolant lines to heat pump assembly fittings. Install new hose clamps if required. Torque coolant line fittings and hose clamps to specification. Ensure connections are fully seated.
    Torque spec

    Coolant Line Fittings15 Nm (11 lb-ft)

    Hose Clamps3 Nm (2 lb-ft)
13. 13

    Reconnect refrigerant lines
    Remove caps from refrigerant ports. Connect all four refrigerant lines to heat pump assembly using new lubricated O-rings. Ensure quick-connect fittings fully engage and lock. Verify each connection is secure by attempting to pull lines away from assembly.
    ℹ️Listen and feel for distinct click when quick-connect fittings engage properly.
14. 14

    Evacuate and charge refrigerant system
    Connect vacuum pump to service ports and evacuate system to 500 microns for minimum 30 minutes. Monitor for vacuum hold to verify no leaks. Charge system with specified amount of R-1234yf refrigerant per underhood label specifications (typically 1.43 lbs). Add refrigerant oil if specified by replacement part instructions.
    ⚠System must hold vacuum for at least 10 minutes after pump shutoff. If vacuum rises, locate and repair leak before charging.

Reassembly

1. Reinstall front fascia lower cover and torque cover screws to specification.
2. Reinstall lower belly pan and secure all fasteners.
3. Reinstall inner fender liner and front passenger wheel. Torque wheel lug nuts to manufacturer specification.
4. Lower vehicle from jack stands.
5. Refill coolant system with ACDelco DEX-COOL to proper level. Bleed air from cooling system per manufacturer procedure.
6. Reinstall high-voltage service disconnect under rear seat.
7. Reconnect 12V battery negative terminal.

Verification

• Use scan tool to clear any diagnostic trouble codes and verify no new codes present.
• Start vehicle and verify heat pump compressor engages when climate control is activated in heat mode.
• Monitor coolant temperature and verify proper circulation through heat pump circuit.
• Check all refrigerant line connections for leaks using R-1234yf leak detector.
• Verify cabin heating and cooling functions operate normally across all temperature settings.
• Test HVAC system in both heat pump mode and auxiliary heat mode to confirm proper operation.
• Inspect all connections for coolant or refrigerant leaks after 15 minutes of operation.
• Verify coolant level remains stable after system reaches operating temperature.

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