BTR4022 - Heater Bypass Coolant Valve – V8Description: Heater Bypass Coolant Valve for V8 petrol applications. This vacuum operated valve is installed in the HVAC coolant circuit and controls the flow of engine coolant to the heater core. In the bypass position it diverts coolant away from the heater core; when commanded open it allows hot coolant through, enabling cabin heating. The valve is actuated by the heater control vacuum circuit and works in conjunction with the heater control