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Freezer Evaporator Fan
The position of the fan blade in relation to the
shroud is important.
0.8 cm ± 0.1
Blade tip
2.5 cm ± 0.1 Target
The evaporator fan is the same fan used on
previous models; however, a signifi cant differ-
ence is that the main control board neither
requires nor receives input from the fan feed-
back/rpm (blue) wire. The fan utilizes a perma-
nent magnet, 4 pole, DC motor that operates at
three different speeds: high, medium, and low.
The speed of the fan is controlled by the voltage
output from the main control board. Voltage
output from the main 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 effec-
tive voltage being received at the motor, which is
equivalent to a reduction in voltage.
13.6 VDC
9.5 VDC
0 VDC
13.6 VDC
8 VDC
0 VDC
Medium Speed (8 VDC measured)
13.6 VDC
6.5 VDC
0 VDC
Orifice
Air Flow
Motor
High Speed (9.5 VDC measured)
Low Speed (6.5 VDC measured)
Fan speed is selected and maintained by the
main control board regulating the length and
frequency of the 13.6 VDC pulse. Temperature
can cause some fan speed variation. Fan speed
can vary +/- 5%, depending on the temperature,
with higher temperatures causing slightly higher
speeds.
The evaporator fan has a 4-wire connection:
White Wire (DC Common)
The white wire is the DC common wire used
for testing. During repairs, DC polarity must be
observed. Reversing the DC polarity causes a
shorted motor and/or board.
Red Wire (Supply)
Each motor uses an internal electronic controller
to operate the motor. Supply voltage from
the main control board remains at a constant
13.6 VDC.
Blue Wire (Feedback/RPM)
On previous Arctica models, the blue wire
reported rpm (speed) information to the main
control board for speed control purposes. On
this model, the board does not require or read
any feedback information from the fan motor.
Yellow Wire (Signal)
The yellow wire is the input wire from the main
control board. The main control board provides
6.5 VDC effective voltage for low speed, 8 VDC
effective voltage for medium speed, and 9.5
VDC effective voltage for high speed. The fan
operates in low speed only when the fresh food
thermistor is satisfied.
Note: When testing these motors:
• You cannot test with an ohmmeter.
• DC common is not AC common.
• Verify 2 voltage potentials:
a. Red to white - power for
b. Yellow to white - power for fan
• Observe circuit polarity.
• Motors can be run for short periods
using a 9 volt battery. Connect the
white wire to the negative (-) battery
terminal only. Connect the red and
yellow wires to the positive (+) battery
terminal.
– 20 –
internal controller
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