Mercedes-Benz W204 air conditioning not cooling
Mercedes-Benz W204: why is the air conditioning not cooling?
The cause varies. The most common are a faulty pressure sensor, also called the pressure switch, a seized compressor and low refrigerant. Topping up refrigerant does not always help, so first find out with service gauges or a diagnostic tool which part is faulty.
Mercedes-Benz W204: how is a pressure sensor fault recognised and fixed?
The symptoms are no cold from the A/C, the blower running continuously or the A/C light blinking. The sensor is under the condenser core. The system is emptied before the sensor is removed and refilled after replacement, so the job is done by an A/C service.
Mercedes-Benz W204: how can I tell that the compressor is broken?
The compressor pulley acts as a mechanical fuse: if the compressor seizes, the pulley slips or breaks. When the A/C is on, the compressor hub should turn. If it does not turn, the compressor is not receiving a control signal or is damaged.