What does large amounts of black dust around the clutch plate indicate?

The presence of large amounts of black dust around the clutch plate typically indicates that the A/C belt is slipping. When the belt does not maintain a proper grip on the pulleys, it generates friction. This friction can cause the rubber material of the belt to wear down, leading to the formation of black dust. Such wear suggests that the belt may be misaligned, overly worn, or not properly tensioned, which results in slippage during operation.

While the other options may relate to different issues within the A/C system, they do not directly correlate with the presence of black dust around the clutch plate in the same way slipping of the belt does. For example, a leaking compressor seal or a defective compressor clutch bearing might create other signs such as the presence of oil or unusual noises, whereas a restriction in the high side could lead to pressure imbalances but wouldn’t typically produce black dust. Therefore, slipping of the A/C belt is the most logical explanation for the noted symptoms.