One of the two fans underneath my laptop computer began making some TERRIBLE grinding noises, so I unscrewed the laptop’s case, and vacuumed out a big clot of dust and debris from the fan’s housing.

This did not actually solve the problem entirely; it was still making loud whirring noises whenever it was rotating quickly (though it was largely quiet before its high-speed setting kicked in).

Then I simply shut the computer off for 24 hours. When I restarted it, it made the same terrible whirring noises, but after about four hours of operation, the fan suddenly returned to its normal noise levels.

The fans are still operational and my diagnostic software says the computer temperature is at normal levels, so, it seems to be operating correctly.

What happened? Is it possible for a fan problem to linger after an obstruction is removed, then spontaneously resolve itself later on?

This particular laptop is somewhat older (about 4 years of age).