This procedure covers the removal and replacement of the heater control valve on a 2021-2024 Ford F-150 with the 3.5L EcoBoost V6 engine, including coolant system draining and refilling.

Warnings

Tools required

Parts

• Heater control valve × 1 — Motorcraft YF-3625 or equivalent
• Coolant hose clamps (worm gear style) × 2 — Use OEM specification
• Shop towels or rags × 1 — N/A

Fluids

• Motorcraft Orange Coolant — 2 qt

Preparation

1. Ensure engine is completely cold to the touch (minimum 2 hours after last operation)
2. Park vehicle on level surface and engage parking brake
3. Place coolant drain pan under radiator drain petcock
4. Remove engine cover by pulling upward on retaining clips
5. Locate heater control valve on passenger side firewall where heater hoses connect

Procedure

1. 1

   Relieve cooling system pressure
   Slowly rotate the radiator cap counterclockwise to the first detent and allow any residual pressure to escape. Wait until no more hissing is heard, then remove cap completely. Verify engine is cold by touching upper radiator hose.
2. 2

   Drain coolant from system
   Open the radiator drain petcock at the bottom of the radiator by turning counterclockwise. Allow approximately 2-3 quarts of coolant to drain into the drain pan. You do not need to drain the entire system, only enough to lower coolant level below the heater control valve. Close drain petcock when coolant stops flowing.
   Torque spec

   Drain Petcock8 Nm (6 lb-ft)
3. 3

   Remove air intake duct (if required)
   If the heater control valve access is obstructed, loosen the clamp at the throttle body and air filter housing. Remove the air intake tube by pulling it off both connections and setting it aside. This provides better access to the valve and heater hoses.
4. 4

   Disconnect electrical connector
   Locate the electrical connector on the heater control valve body. Press the locking tab and pull the connector straight off the valve. Do not pull on the wiring harness. Move the connector aside to prevent damage during valve removal.
5. 5

   Remove inlet heater hose
   Using hose clamp pliers, compress and slide the spring clamp back approximately 2 inches on the inlet heater hose (upper hose from engine). Twist the hose gently while pulling to remove it from the heater control valve inlet port. Have shop towels ready to catch residual coolant. Inspect the hose end for cracks or deterioration.
6. 6

   Remove outlet heater hose
   Using hose clamp pliers, compress and slide the spring clamp back approximately 2 inches on the outlet heater hose (hose going to heater core). Twist the hose gently while pulling to remove it from the heater control valve outlet port. Allow residual coolant to drain into your drain pan or towels.
7. 7

   Remove heater control valve mounting
   Locate the mounting bracket bolt(s) securing the heater control valve to the firewall or mounting bracket. Remove the mounting hardware using the appropriate socket. The valve may be held by one or two bolts depending on the specific bracket design. Remove the old heater control valve from the vehicle.
   Torque spec

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

   Prepare and install new heater control valve
   Compare the new heater control valve to the old unit to verify correct replacement part. Note the inlet and outlet port orientations. Position the new valve in the mounting bracket with ports oriented correctly (inlet from engine, outlet to heater core). Install mounting bolt(s) and torque to specification.
   Torque spec

   Valve Mounting8 Nm (6 lb-ft)
9. 9

   Connect heater hoses
   Install the inlet heater hose onto the valve inlet port, pushing firmly until the hose is fully seated against the valve shoulder. Slide the hose clamp into position approximately 1/4 inch from the end of the hose. Repeat for the outlet hose. If using new worm-gear clamps, position them in the same location and torque to specification.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
10. 10

    Reconnect electrical connector
    Plug the electrical connector onto the heater control valve until you hear and feel a positive click. Gently tug on the connector to verify it is locked in place. Ensure no wiring is pinched or stretched.
11. 11

    Reinstall air intake components
    If the air intake duct was removed, reinstall it by pressing it onto the throttle body and air filter housing connections. Tighten the clamps securely. Ensure all connections are properly seated.
12. 12

    Refill cooling system
    Using a funnel, add Motorcraft Orange Coolant to the radiator until the level reaches the bottom of the radiator neck. Add coolant to the overflow reservoir to the COLD FULL mark. Install the radiator cap by pressing down and turning clockwise until it locks into place.
13. 13

    Bleed air from cooling system
    Start the engine and allow it to reach normal operating temperature with the heater set to maximum heat and fan on high. Monitor the temperature gauge to ensure it remains in the normal range. Watch for coolant circulation in the reservoir. Run engine for 10 minutes, then shut off and allow to cool for 30 minutes. Recheck coolant level and add as necessary to maintain proper level.

Reassembly

1. Verify all hose clamps are properly positioned and tightened
2. Confirm electrical connector is fully seated and locked
3. Reinstall engine cover by aligning clips and pressing down until seated
4. Inspect ground under vehicle for any coolant drips or leaks

Verification

• Start engine and verify no coolant leaks at heater control valve connections
• Turn heater controls to maximum heat and verify hot air comes from vents within 5 minutes of engine warm-up
• Turn heater to cold and verify air temperature decreases, indicating valve is modulating properly
• Check coolant level in overflow reservoir when engine is cold - should be at COLD FULL mark
• Scan for diagnostic trouble codes related to heater control valve operation using an OBD-II scanner
• Monitor engine temperature gauge during a test drive to confirm normal operating temperature is maintained

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