The compressor of the air conditioner is engaged by the A/C clutch, which is part of the drivebelt pulley but usually does not need adjustment; although, in case the pulley has been changed, the clearance between the pulley and the clutch plate must be checked. The clearance ought to be confirmed to be ranging between 0.6 and 1.0 mm in the presence of a feeler blade with the engine and air conditioner off (0.024 and 0.040 in). In case it requires changes, unscrewing the nut to fit the nut and the number of shims can be altered and the nut refitted back before screwing the nut again.