1. Heater Control Valve (HCV) Failure: The HCV controls the flow of hot coolant from the engine to the left side heater core. If the valve is faulty or stuck open, it may allow hot coolant to flow to the left heater core even when the AC is on, resulting in warm air from the left vents.
2. Faulty Blend Door Actuator: The blend door actuator controls the mixing of hot and cold air to achieve the desired temperature. If the actuator fails, it cannot properly adjust the blend door, resulting in warm air coming out of the left vents.
3. Refrigerant Leak: A refrigerant leak in the AC system can cause insufficient cooling and a lack of cold air from the vents. This could lead to warm air coming out of the left vents, especially if the system is low on refrigerant.
4. AC Compressor Issues: A failing or faulty AC compressor can affect the cooling capacity of the entire AC system. If the compressor is not functioning properly, it can lead to reduced cooling and warm air from the vents.
5. Temperature Sensor Malfunction: The temperature sensor monitors the cabin temperature and provides input to the climate control system to regulate airflow and temperature. A faulty temperature sensor may provide incorrect readings, resulting in improper AC operation and warm air from the left vents.
6. Electrical Problems: Faulty electrical connections or damaged electrical components in the climate control system can also contribute to this issue. Electrical issues can affect the function of various components, leading to inconsistent temperature and warm air from the left vents.
To diagnose the root cause of this problem accurately, it is recommended to have your car inspected by a qualified mechanic or visit an authorized Mercedes-Benz dealership. They can use diagnostic tools to assess the health of the AC system and identify any underlying issues.
