Heater Control Valve

This procedure covers the removal and replacement of the heater control valve on a 2014-2018 Chevrolet Silverado 1500 with the 5.3L V8 EcoTec3 engine, including coolant drainage and refill.

Warnings

Tools required

Parts

• Heater control valve × 1 — ACDelco 15-73598 or equivalent
• Hose clamps × 2 — Use OEM specification
• DEX-COOL engine coolant × 1 — ACDelco DEX-COOL Orange

Fluids

• ACDelco DEX-COOL (Orange) — 2 qt

Preparation

1. Ensure engine is completely cold to the touch
2. Park vehicle on level surface and engage parking brake
3. Place drain pan under radiator drain petcock
4. Locate heater control valve on firewall near heater core inlet/outlet hoses
5. Have shop towels ready to catch residual coolant spillage

Procedure

1. 1

   Drain cooling system
   Open the radiator drain petcock at the bottom of the radiator and drain approximately 2 gallons of coolant into the drain pan. This is sufficient to lower coolant level below the heater control valve. Close the petcock when finished.
   Torque spec

   Drain Petcock8 Nm (6 lb-ft)
2. 2

   Relieve cooling system pressure
   Carefully remove the radiator cap to fully relieve any remaining pressure in the cooling system. Set cap aside in a clean location.
3. 3

   Disconnect electrical connector
   Locate the electrical connector on the heater control valve. Press the release tab and pull the connector straight off the valve. Move the connector out of the work area.
4. 4

   Remove inlet hose clamp
   Using hose clamp pliers, compress or loosen the hose clamp on the inlet heater hose at the valve. Slide the clamp back along the hose away from the valve fitting. Note the orientation of the hose for reassembly.
   ⚠Residual coolant will drain from hoses when disconnected. Keep drain pan and towels ready.
5. 5

   Remove outlet hose clamp
   Using hose clamp pliers, compress or loosen the hose clamp on the outlet heater hose at the valve. Slide the clamp back along the hose away from the valve fitting.
6. 6

   Disconnect heater hoses
   Twist and pull both heater hoses off the valve fittings. Allow residual coolant to drain into the pan. Plug hose ends with shop towels or rags to minimize coolant loss and prevent contamination.
7. 7

   Remove valve mounting fasteners
   Remove the mounting bracket bolt(s) securing the heater control valve to the firewall or mounting bracket. The valve may be held by one or two fasteners depending on configuration.
   Torque spec

   Valve Mounting8 Nm (6 lb-ft)
8. 8

   Remove heater control valve
   Pull the heater control valve away from the mounting location. Inspect the mounting bracket for damage or corrosion. Clean the mounting area if necessary.
9. 9

   Install new heater control valve
   Position the new heater control valve in the mounting bracket, aligning the mounting holes. Install the mounting bolt(s) and torque to specification. Ensure the valve inlet and outlet ports are properly oriented to match the heater hoses.
   Torque spec

   Valve Mounting8 Nm (6 lb-ft)
10. 10

    Connect heater hoses
    Push both heater hoses firmly onto the valve fittings until they are fully seated. Ensure hoses are routed correctly without kinks or sharp bends. Slide new hose clamps into position approximately 1/4 inch from the end of each hose.
11. 11

    Secure hose clamps
    Using hose clamp pliers or a screwdriver, tighten both hose clamps to specification. Ensure clamps are positioned over the raised bead on the valve fittings for proper sealing.
    Torque spec

    Hose Clamps3 Nm (2 lb-ft)
12. 12

    Reconnect electrical connector
    Push the electrical connector onto the heater control valve until it clicks into place. Verify the connector is fully seated and the locking tab is engaged.
13. 13

    Refill cooling system
    Fill the cooling system with DEX-COOL orange coolant through the radiator fill neck. Add coolant slowly to allow air to escape. Fill to the cold fill line on the overflow reservoir. Install the radiator cap securely.
14. 14

    Bleed cooling system
    Start the engine and allow it to reach normal operating temperature with the heater set to maximum heat. Monitor coolant level and add as necessary. Watch for leaks around the heater control valve connections. Run engine until the thermostat opens and coolant circulates fully.
    ⚠Keep hands and tools away from moving fan blades and hot engine components during warm-up.

Reassembly

1. Verify all hose clamps are tightened to specification
2. Confirm electrical connector is fully engaged with locking tab seated
3. Check that heater hoses have no kinks or interference with other components
4. Top off coolant overflow reservoir to the cold fill line after engine cools

Verification

• Start the engine and verify no coolant leaks at the heater control valve connections
• Test heater operation by setting climate control to maximum heat and verify hot air flow from vents
• Monitor engine temperature gauge to ensure normal operating temperature is maintained
• Check coolant level in overflow reservoir after test drive and top off if necessary
• Verify no coolant drips or stains appear under vehicle after overnight parking

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