Programming instructions

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Programming variable stages
Before programming variable stages, make sure you have them properly configured. For more
information, read Configuring variable stages on page 18.
How variable cooling stages work
 When the temperature is below the idle range, the fan is off.
 When the temperature reaches the idle range, the fan runs at the idle speed. The fan continues to
run at the idle speed until the temperature rises to the set point.
 When the temperature is between the set point and differential, fan speed increases or decreases
proportionally with the temperature.
 When the temperature is at or above the differential, the fan runs at full speed.
 The set point and differential must be greater than the idle range.
 If there is not much difference between the set point and differential, the fans can
suddenly jump in speed. For example, if there is only a 0.1° difference between
the two settings, the fans can jump from 50 to 80% because of the tight range.
0100
Temperature
Fan speed
Fan speed increases as the temperature rises, or
decreases as the temperature falls.
The fan runs at idle speed
The fan is off
The fan runs at full speed
Differential
Idle range
Idle speed
Set point