Does anyone know the reason why the passenger heater of BMW 320li does not come out?

The reason why the car does not produce warm air may be that the filter is clogged, or the blower is not running at various speeds, or the heater box is malfunctioning. Warm air blows the heat from the heater water tank into the cab through a blower. If the air volume is insufficient or the hot and cold air distribution is not good, the heat from the heater water tank cannot be dissipated, and warm air cannot come out of the car.

The thermostat opens too early, causing the cooling system to perform a large cycle too early. When the external temperature is low, the cold air will quickly cool the antifreeze, and the engine water temperature cannot rise, so there is no warmth. The impeller of the water pump is damaged or lost, resulting in insufficient flow through the heater water tank and no heat.

Extended information:

Heat pipe heating system: The heat pipe heat exchanger is installed vertically in the car floor. Above the floor is the condensation and heat release section, and below the floor is the exhaust gas heating part. The exhaust gases from the automobile engine exhaust pipe are introduced into the heat pipe exchanger, which contains liquid ammonia.

After being heated, the liquid ammonia vaporizes and reaches the upper part of the heat pipe exchanger to exchange heat with the air, heating the air coming in from the vent. After the air is heated, it is blown into the cabin by the blower for heating. After the heat is released, the ammonia gas condenses and flows back to the lower part, and then completes the next working cycle.

Baidu Encyclopedia-Car Heating System