CITROEN C4 2004 Handbook page 405

CHECKING THE EFFICIENCY OF THE AIR CONDITIONING SYSTEM
Principal problem
The aircon compressor makes
an abnormal noise
Aircon circuit diagnosis table
Symptom
The clutch of the aircon compressor remains
engaged
The clutch of the aircon compressor remains
engaged and slips
402
Possible causes
Incorrect adjustment of the aircon compressor
clutch
Aircon fluid quantity
Aircon compressor defective
Lack of aircon fluid in the aircon circuit
Aircon compressor valves defective
Aircon compressor clutch
Auxiliaries drive belt