The make-up of the continuously driven clutch-less pulley means it contains no electromagnet to engage the compressor clutch, when requested by the vehicle climate control system. Therefore, by means of rubber bushings contained within the drive pulley itself, the initial start-up load imparted on the compressor is dampened, when the solenoid actuates the swash plate within the compressor, due to the vehicle climate controls requesting it.

 

Problems with these components can lead to intermittent rattling or knocking in the engine bay area. Generally the most common component failures causing this are the alternator clutch pulley, auxiliary belt tensioning pulley and air conditioning pulley.

 

Where this occurs, technicians should check for noise and movement coming internally from the A/C pulley on the clutch-less compressors on for example Audi, Mercedes, Toyota, Opel, BMW, Seat, Skoda, VW and other systems, even though the air con is working as per manufacturers recommendations.

 

If it is proven that the air-con pulley is the root cause of the problem, it is recommended to replace as a complete assembly, due to the dampers breaking up internally. Owing to the fact that vibration and shock loading is imparted on the pulley and bearing whilst the unit is initially failing, it is advised to replace the complete pulley not just the dampers to guarantee reliability.

 

Technicians should also check the alternator clutch pulley and auxiliary belt tensioner, as failure of either of these components may result in damage to the air conditioning drive pulley.

 

Replacement components for this common repair are in stock and available from Auto Air. For more information call 01-825-0543 or visit www.autoair.ie.