Between the engine main water tank and the heater water tank. According to the Teana official website, the 2008 Teana warm air and water valve is the warm air switch of the car heater. It is located between the engine main water tank and the heater water tank. It can prevent the coolant in the engine from entering the heater water tank and prevent the temperature of the cab from rising. high. Teana is a mid-to-high-end luxury sedan produced by Nissan.