Please, do not directly spray water onto anything that has a sealed ball bearing in it. This would include the alternator, the A/C compressor clutch, the belt tensioner, and even the water pump (although it's well shielded). Contrary to popular opinion, the seals on ball bearings are not designed to operate while submerged, and they are not designed to withstand a direct spray of water. Helk, many bearing seals have small vents in them to allow air pressure to equalize when the bearing heats up. Those vents can also let water in to the bearing when it is directly exposed.
I currently work in the bearing industry, and I can't tell you how many times I've had to explain this to automotive customers. If you hit your alternator with high pressure water, don't be surprised if the bearings are making noise soon thereafter.
Hope this helps someone...
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