Heater Control Valve

Remove and replace the heater control valve on a 2008 Dodge Viper 8.4L V10, including coolant drain and refill procedures.

Warnings

Tools required

Parts

• Heater control valve × 1 — Use OEM specification
• Hose clamps (if damaged during removal) × 2 — Use OEM specification

Fluids

• Mopar HOAT coolant 50/50 — 2 qt

Preparation

1. Ensure engine is completely cold to the touch
2. Position vehicle on level ground
3. Place drain pan under radiator drain plug location
4. Have shop towels ready to contain coolant spillage during valve removal

Procedure

1. 1

   Drain cooling system partially
   Open the radiator drain plug (petcock) located at the lower driver side of the radiator and drain approximately 2 gallons of coolant into the drain pan. This will lower the coolant level below the heater control valve to minimize spillage. Close the drain plug once sufficient coolant has been drained.
2. 2

   Locate heater control valve
   The heater control valve is located on the passenger side of the engine bay, in the heater hose circuit between the engine and the heater core. It is mounted on or near the firewall with two coolant hoses connected to it. The valve has a vacuum line or electrical connector controlling its operation.
3. 3

   Disconnect control mechanism
   Disconnect the vacuum line from the heater control valve by pulling it straight off the nipple. If the valve is electrically actuated, disconnect the electrical connector by depressing the locking tab and pulling it free. Note the orientation for reinstallation.
4. 4

   Remove inlet hose clamp
   Using pliers or hose clamp pliers, slide the hose clamp on the inlet side (engine side) of the heater control valve back along the hose at least 2 inches away from the valve connection point. If using a worm-drive clamp, loosen it with a screwdriver or socket.
5. 5

   Remove outlet hose clamp
   Using pliers or hose clamp pliers, slide the hose clamp on the outlet side (heater core side) of the heater control valve back along the hose at least 2 inches away from the valve connection point. If using a worm-drive clamp, loosen it with a screwdriver or socket.
6. 6

   Remove valve mounting fasteners
   Remove the mounting bracket fasteners securing the heater control valve to the firewall or mounting bracket. These are typically 2 fasteners. Have shop towels ready to catch residual coolant.
7. 7

   Remove heater control valve
   Twist and pull the inlet hose off the heater control valve inlet nipple. Immediately place your thumb over the hose end or point it into the drain pan to minimize coolant loss. Twist and pull the outlet hose off the valve outlet nipple. Remove the valve from the engine bay. Allow any remaining coolant to drain into the pan.
8. 8

   Install new heater control valve
   Position the new heater control valve in the mounting location with the inlet and outlet oriented correctly (inlet toward engine, outlet toward heater core). Install the mounting bracket fasteners and tighten securely. Push the inlet hose firmly onto the valve inlet nipple until it seats completely, then slide the hose clamp into position over the connection. Push the outlet hose firmly onto the valve outlet nipple until it seats, then slide the hose clamp into position over the connection.
9. 9

   Secure hose clamps
   Ensure both hose clamps are positioned approximately 1/4 inch from the end of each hose connection on the valve. Tighten worm-drive clamps securely with a screwdriver or socket, or ensure spring clamps are fully seated past the bead on the nipple.
10. 10

    Reconnect control mechanism
    Reconnect the vacuum line to the heater control valve nipple, pushing it on until it seats firmly. If electrically actuated, reconnect the electrical connector until it clicks into place.
11. 11

    Refill cooling system
    Using a funnel at the radiator cap opening, add Mopar HOAT 50/50 coolant mixture to the cooling system. Fill slowly to allow air to escape. Fill to the cold fill line on the coolant recovery reservoir. Install the radiator cap.
12. 12

    Bleed cooling system
    Start the engine and allow it to warm up to operating temperature with the heater on maximum heat setting. Monitor the coolant level in the recovery reservoir. Add coolant as needed to maintain proper level. Run the engine until the thermostat opens and coolant circulates through the entire system. Check for leaks at the heater control valve connections.
13. 13

    Final coolant level check
    After the engine reaches operating temperature and the cooling fans cycle at least once, turn off the engine and allow it to cool for 30 minutes. Check the coolant level in the recovery reservoir and top off to the cold fill line if necessary. Inspect all connections at the heater control valve for any signs of seepage.

Reassembly

1. Ensure both heater hoses are firmly seated on the valve nipples with clamps properly positioned
2. Verify vacuum line or electrical connector is securely attached
3. Confirm cooling system is filled to proper level and fully bled of air

Verification

• Start engine and verify no coolant leaks at heater control valve connections after reaching operating temperature
• Test heater operation by switching between maximum heat and maximum cold settings, confirming temperature change at vents
• Check coolant level in recovery reservoir after test drive and top off if necessary
• Verify coolant level remains stable after several heat cycles with no loss indicating leaks

Related trouble codes on this vehicle

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