The air conditioning system produces an inappropriate noise (Step 3 – Base Table B)


Noises heard when the air conditioning system is switched on are not necessarily a sign of a fault. However, if the noise remains after a few minutes, check whether one of the following reasons is causing an operating fault and test the proposed solution.

The V-belt is slipping or worn.

Check that the belt is sufficiently tensioned and that it is positioned straight on the pulley.

The ball bearing in the belt tensioner causes noise.

Replace the bearing.

Compressor magnetic coupling slips.

Check the distance between the belt pulley and the drive plate. It must be configured to between 0.4-0.6 mm (refer also to “Technical documentation for AC systems in vehicles”).

Vibration noise from the compressor base.

Check that all nuts and bolts are properly tightened. Check that the belt pulley is even (see installation instructions).

The expansion valve "makes noise".

If the noise continues: Replace the valve (see Worksheet 3).

Noises from the drain hose for the condensate.

Equip the drain hose for condensate with a “check valve”. In this way the condensate is lead out and is not sucked return, which would otherwise cause a gurgling sound.


In the following circumstances, malfunctions cause abnormal suction and high pressure on some of the air conditioner’s components. This phenomenon causes noise at the compressor, which is not caused by the compressor. The following reasons cause the noise.

The refrigerant volume is not correct (30 – 35% too much or 70 – 75% too little).

The expansion valve is closed, blocked or clogged

The compressor's suction pressure regulator is defective (only for compressors with a suction pressure regulator (V)).

Stoppage in the air conditioner system's refrigerant circuit.

The filter is saturated with moisture.


If the noise continues, despite inspection and possible rectification of the possible causes listed above, contact WAECO’s technical service department.

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