Screw air compressor fan direction

A screw compressor works with a male and female rotor that rotate in the opposite direction. This movement draws in air that is compressed as the space between the rotors and their housing decreases. The compressed air is then displaced to the outlet. [pdf]

Screw air compressor fan short circuit to ground

Try to turn the compressor by hand. It should be possible to turn it around. It should turn around smoothly, without any 'hickups' (be sure to completely shut down the air compressor!). Check the isolation of the motor windings. [pdf]