Fault diagnosis device and a failure diagnosis method of the air conditioner compressor for a vehicle

摘要

PROBLEM TO BE SOLVED: To accurately determine fault due to sticking or the like of a compressor for an air conditioner.SOLUTION: When detecting the lowering of an engine speed at a predetermined lowering rate &Dgr;NE1 or more during operation of a compressor for an air conditioner (t1), the operation of the compressor is stopped to avoid the occurrence of the engine stall, and the compressor is operated again after elapse of a first predetermined time &Dgr;T1 (t2). When detecting an engine speed increase at a predetermined increase rate &Dgr;NE2 or more (t4), following the lowering of the engine speed at the predetermined lowering rate &Dgr;NE1 or more (t3), in a second predetermined time &Dgr;T2 from the re-operation of the compressor, the fault due to the sticking of the compressor is determined. In this way, when the number of times determined as fault reaches a predetermined number of times (t7), the fault of the compressor is decided.