12
Condenser Fan
Condenser fan speed corresponds with compressor speed (low, medium, high) to
minimize pressure variations in the sealed system except when the freezer
temperature is 20°F above the set point (ex:NEW). If this condition exists (such as
during initial startup), the condenser fan operates at super high speed (12VDC
between white and yellow lead)while the compressor operates at medium speed.
The speed of the fan is controlled by the voltage output from the main control board.
Voltage output from the control board to the fan is 13.6 VDC; however, to regulate
the speed of the fan, the main control board uses pulse width modulation (PWM).
When operating, voltage is sent in pulses (much like a duty cycle) as opposed to an
uninterrupted flow. This pulsing of 13.6 VDC produces effective voltage being
received at the motor, which is equivalent to a reduction in voltage.
Fan speed is selected and maintained by the main control board regulating the
length and frequency of the 13.6 VDC pulse.
mabe CONFIDENTIAL AND PROPRIETARY INFORMATION-NOT FOR PUBLIC DISCLOSURE. January 2008