Additional Heater Assembly Description (K9K Model)
The heat of the engine coolant is used to warm up air through the heater core so that the warmed air is blown into the inside of the vehicle. The engine coolant temperature increases slower in diesel engine; therefore, air through the heater core cannot be warmed up sufficiently.
To improve the warming performance, the vehicle is equipped with the additional heater assembly (1). After its activation by ECM, the engine coolant is warmed up additionally and more heat is added to air through the heater core. It is not activated during pre/post heating by glow plug. Not during pre/post heating by glow plug, it is activated on the following conditions.
Ten seconds have passed after the engine start.
The battery voltage is more than 12.2 V.
The engine speed is more than 700 rpm.
The engine coolant and the intake air temperature is as shown in the graph below.
[A]: Engine coolant temperature (°C) [C]: ON
[B]: Intake air temperature (°C) [D]: OFF