Mercedes-Benz W203 air conditioning not cooling
Mercedes-Benz W203: why is the air conditioning not cooling?
The most common causes are a refrigerant leak (for example from the condenser, the core in front of the radiator), a fault in the compressor or its electrical connection, and EC mode being on. Start with the EC mode and the compressor connector, then the leak test.
Mercedes-Benz W203: what does the EC light mean and why does no cold air come?
EC is the Economy mode, in which the compressor does not run, so the air is neither cooled nor dried. When the climate control is in automatic, the EC light must be off. The light can be switched off with the EC button. If the compressor still does not engage, the wiring connections of the magnetic clutch are worth checking.
Mercedes-Benz W203: why does the air conditioning work only when driving?
If the condenser fan does not run when stationary, the pressure in the air conditioning rises too high and the compressor switches off. The fan operation is worth checking first. An electrical fault in the compressor connector can be diagnosed with a Star tester before replacing the compressor.
Mercedes-Benz W203: how do you locate an air conditioning refrigerant leak?
When the system is empty, the leak is looked for with a pressure test before filling. Typical leak points are the compressor shaft seal, the pipe passages and the condenser. When the system has been empty or the condenser is replaced, also replace the drier, which absorbs moisture.