Mercedes-Benz W124 air conditioning not cooling or compressor not engaging
Why is the Mercedes-Benz W124 air conditioning not cooling?
The most common cause is too little refrigerant, either from a leak or natural loss. Typical signs are air bubbles in the sight glass and the compressor cycling more often than usual. A leaking condenser is common, as it is sensitive to stone chips.
Why does the Mercedes-Benz W124 air conditioning compressor not engage?
First check whether there is enough refrigerant and whether the outside air is above about +8 degrees, because the intake air thermostat prevents starting when it is cold. Other causes are a broken magnetic clutch coil wire, a faulty pressure sensor, a missing belt, and the 10 A fuses of the relay behind the battery and of the overvoltage protection.
How do you find a leak in the Mercedes-Benz W124 air conditioning and what should be noted during service?
The leak is found by pressurising the system with nitrogen and looking for soap bubbles on the condenser and lines. The protective plugs of the drier are not opened until the part is installed, and during service the amount of compressor oil must be confirmed: lack of oil is the most common cause when the compressor seizes after service.