The noise does suggest dust on fan blades. Consequently, as O_G has indicated, best to avoid the washing machine and carefully 'hand wash'. Furthermore, he has given excellent advice about avoiding the fan blades spinning. If you should use an airblaster, it is advisable to hold the blades with thumb and forefinger when blasting away.
It would be wonderful if Computer manufacturers were to incorporate a removable dust filter which could be hand washed. A simple thing I would have thought......but comps might then last longer, and that's not what manufacturers want.
Ron.
Ron.