I have a 320d pre-facelift with M47 engine and my A/C Compressor making a strange whining noise when the clutch is engaged.
This whining noise changes its pitch with the engine RPM and when it happens I get poor cooling too.
I have changed everything except for the A/C compressor including evaporator, condenser, expansion valve, filter and cleaned all the hoses.
I read some says it happens when lack of oil/lubrication in the compressor or when low on freon, but I have topped them up too (not sure if it leaks)
Can anybody help me to troubleshoot this issue as it's a real headache now for almost a month?