This procedure covers the removal and replacement of the heater control valve on a 2016-2024 Hyundai Tucson with the 2.5L I4 engine and AWD system.

Warnings

Tools required

Parts

• Heater control valve × 1 — Use OEM specification
• Heater hose clamps (if reusing is not possible) × 2 — Spring-type or worm-drive clamps

Fluids

• Hyundai/Kia Long Life Coolant (Green) — 2 qt

Preparation

1. Ensure engine is completely cold (wait at least 3 hours after last operation)
2. Park vehicle on level ground and engage parking brake
3. Open hood and locate heater control valve on passenger side firewall near heater hoses
4. Place drain pan under work area to catch coolant spillage
5. Remove engine cover by pulling upward on front and rear pull tabs

Procedure

1. 1

   Relieve cooling system pressure
   Slowly open the radiator cap or coolant reservoir cap by turning counterclockwise to the first stop. Wait for any residual pressure to release completely, then remove the cap fully. This prevents pressurized coolant from spraying when hoses are disconnected.
2. 2

   Drain coolant from system
   Position drain pan under radiator drain plug located at bottom of radiator on driver side. Open drain plug and allow approximately 2-3 quarts of coolant to drain. This reduces the amount of coolant that will spill when disconnecting heater hoses. Close drain plug finger-tight for now.
3. 3

   Disconnect electrical connector
   Locate the electrical connector on the heater control valve body. Press the release tab and pull connector straight off the valve. Do not pull on wires. Move connector aside to prevent damage during removal.
4. 4

   Remove inlet heater hose
   Using hose clamp pliers or screwdriver, loosen the hose clamp on the inlet heater hose (upper hose from engine). Slide clamp back along hose at least 2 inches. Twist hose gently to break seal, then pull straight off the valve inlet nipple. Some coolant will drain; direct into drain pan.
5. 5

   Remove outlet heater hose
   Loosen the hose clamp on the outlet heater hose (lower hose to heater core). Slide clamp back along hose. Twist and pull hose off the valve outlet nipple. More coolant will drain at this point.
6. 6

   Remove valve mounting hardware
   Remove the mounting bolt or bracket securing the heater control valve to the firewall or mounting bracket using a 10mm socket. Support the valve with one hand while removing the fastener to prevent it from dropping.
   Torque spec

   Valve Mounting8 Nm (6 lb-ft)
7. 7

   Remove heater control valve
   Pull the heater control valve away from the mounting location. Inspect the valve for the failure mode (stuck open, stuck closed, or leaking) to confirm diagnosis. Tip remaining coolant from valve into drain pan.
8. 8

   Prepare new valve
   Remove new heater control valve from packaging. Verify it matches the old valve in connector type, hose nipple size, and mounting configuration. Inspect hose nipples for any protective caps and remove them.
9. 9

   Install new valve
   Position new heater control valve into mounting location with hose nipples oriented correctly (inlet toward engine, outlet toward firewall). Install mounting bolt or bracket and torque to specification.
   Torque spec

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

    Connect heater hoses
    Push inlet heater hose firmly onto inlet nipple until it seats completely. Slide hose clamp into position 1/4 inch from end of hose and tighten to specification. Repeat for outlet hose. Ensure hoses are fully seated to prevent leaks.
    Torque spec

    Hose Clamps3 Nm (2 lb-ft)
11. 11

    Reconnect electrical connector
    Push electrical connector onto valve terminals until it clicks into place. Tug gently to verify it is locked securely.
12. 12

    Refill cooling system
    Close radiator drain plug if still open. Fill cooling system with Hyundai/Kia Long Life Coolant (Green) through radiator or reservoir until level reaches MAX line. Add coolant slowly to prevent air pockets from forming.
13. 13

    Bleed cooling system
    Start engine with radiator or reservoir cap off. Allow engine to warm up to operating temperature while monitoring coolant level. Add coolant as level drops during bleeding process. Run heater at maximum temperature to circulate coolant through heater core. When cooling fans cycle on and off, system is at operating temperature.
14. 14

    Final coolant level check
    With engine at operating temperature, verify coolant level is at MAX line in reservoir. Top off if needed. Install radiator or reservoir cap. Allow engine to run for 2-3 minutes, then shut off and check for leaks around heater control valve connections.

Reassembly

1. Reinstall engine cover by aligning mounting grommets and pressing down firmly until it clicks into place
2. Wipe any spilled coolant from engine bay components and floor with shop towels
3. Dispose of old coolant at an approved recycling facility

Verification

• Start engine and verify heater control valve operates correctly by testing climate control at various temperature settings
• Confirm hot air flows from vents when heater is set to maximum temperature
• Visually inspect heater control valve and hose connections for any coolant leaks while engine is at operating temperature
• Check coolant level in reservoir after test drive and top off if necessary
• Monitor coolant level over the next few days to ensure no slow leaks are present

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