Introduction:
The following discussion of Wind Baffle use applies to Fujitsu Airstage H-Series and J-Series outdoor units, which
feature a horizontally mounted fan and motor. Wind baffle use does not apply to Airstage V-Series outdoor units,
with a vertically mounted fan and motor.
 

Discussion:
“Windmilling” is an occurrence where the outdoor unit fan rotates opposite of normal direction when the unit is OFF.
This condition is a result of wind gradients, or wind shear conditions. Typically, windmilling may occur at threshold
speeds of 25 MPH (22 knots) and higher, when the outdoor unit fan is at or near perpendicular to the wind
direction. Windmilling which occurs when the outdoor unit remains OFF is not a concern. However, when the unit
turns on, the fan motor torque may not be able to overcome the fan inertia, resulting in a nuisance shutdown of the
system.
 

Installation of wind baffles prevent the outdoor unit fan from “windmilling” in the opposite direction, by effectively
disrupting the wind path into the outdoor unit. Small, resultant eddy currents will have minimal, if no contributing
affect to windmilling.

NOTE– Wind baffle use does not affect low ambient cooling operating range.

See the attachment for more information