BMW E46 Air Conditioning Not Cooling or Compressor Not Engaging
Why is the E46 air conditioning not cooling?
The most common cause is a refrigerant leak, often a pinhole in the condenser. If the system is too empty, the compressor will not start. In older systems the limit is about 1.9–2.8 bar. When running, the pressure should be about 10–15 bar.
Why does the E46 air conditioning compressor not engage?
Causes include low refrigerant, a broken receiver-drier pressure sensor, an oxidised pressure sensor connector and a broken control wire. On a diesel, incorrect vehicle speed data from the front sensor can prevent engagement. Fault codes often point the way.
How do you find an air conditioning refrigerant leak?
A vacuum test is not enough, because the vacuum can suck a leaking seal shut. The leak is found by testing the system with nitrogen, or a small leak with dye. The most common leak point is the condenser.
What causes a hiss or a whistle from the air conditioning?
The noise often comes from the expansion valve. Replacing it together with its O-rings fixed the noise and did not reduce performance. A smell usually comes from the fresh air filter.