What is the cause of no warm air in BMW 5 Series?

[AubreyMarie]

The reasons for no warm air in BMW 5 Series are as follows: Heater core blockage: When the inlet pipe of the heater core is hot while the outlet pipe remains cold, it indicates poor circulation in the air conditioning radiator. The radiator fins of the air conditioning system are very delicate. After prolonged use, scale and impurities in the coolant can clog the radiator's internal passages, leading to poor circulation and insufficient heat transfer to provide warm air for the cabin. This situation constitutes an internal blockage of the air conditioning radiator. Clogged cabin air filter: The primary function of the cabin air filter is to remove impurities from the air entering the air conditioning system. When the filter becomes clogged, insufficient air enters the system, preventing the blower from generating adequate airflow to deliver warm air. Aging blower motor: As the blower motor ages and its efficiency decreases, it may produce loud noise but weak airflow. This prevents timely and effective heat transfer from the heater core to the cabin, resulting in insufficient warm air output.