I would think if the electric fan vibrates it has lost a blade or balancing weight. Usually, electric fans are quiet and pretty much vibration free.
1949 F-4 Built to drive--script bed.
1956 F350 Stock rebuilt script bed
2007 F150 SC. Driven once in a while. 2015 Escape SE EB 1.6 Wife's ride
Government conceived by genius, now operated by fools.