The cooler in the netbook began to make a loud noise, what is the reason?

Question

laptops

It so happened that an hp netbook (can't remember the exact model) got caught in the rain. He was at the open window when it started to rain and was flooded. After checking its performance - plugging it into the network (at my own peril and risk), I find out that it works, the keys are all pressed, the ports are connected (I only checked USB and power). But the fan makes a loud noise, the sound added speed.
What to look for when inspecting the internal components, and why did it start making noise even louder?

Answer 1

The dust on the fan has crumpled from the water and now the cooler is scratching it. When parsing, look carefully for traces of metal oxidation, protect such places with a toothbrush.