GE PFSS9PKY Technical Service Manual page 39

Note: Certain voltmeters will not be able to read
voltage output from the inverter.
The inverter receives 120 VAC line-in from the power
supply. The inverter converts this single-phase, 60
Hz, 120 VAC into 3-phase, 230 VAC, with frequency
variations between 400 Hz and 700 Hz. This voltage
is delivered to the compressor through 3 lead wires.
Each wire will carry identical voltage and frequency.
Note: If the compressor wires are not connected, or
if an open occurs in one of the 3 lead wires or in the
compressor, the inverter will stop voltage output.
The inverter controls compressor speed by
frequency variation and by Pulse Width Modulation
(PWM). Changing frequency and PWM will cause
an effective voltage between 80 and 230 VAC to be
received at the compressor.
• Low speed (1710 rpm) - 400 Hz
• Medium speed (2100 rpm) - 500 Hz
• High speed (3120 rpm) - 700 Hz
The inverter receives commands from the main
control board. The main control board will send
a PWM run signal from the J15 connector of
between 4-6 VDC effective voltage to the inverter
(all wires must be connected). The inverter will select
compressor speed (voltage output) based on this
signal.
The main control board will only send a run signal to
the inverter when the compressor should be on.
Note: When measuring signal voltage (from the
main control board) at the inverter, a reading of
approximately 2.9 VDC will be measured with
all wires connected. If the inverter wiring is
disconnected, the board output will measure
between 10-12 VDC.
The inverter will monitor compressor operation and
if the compressor fails to start or excessive current
draw (4 amps maximum) is detected, the inverter
will briefl y stop voltage output. The inverter will then
make 12 consecutive compressor start attempts
(once every 12 seconds). After 12 attempts, if the
compressor has not started, an 8-minute count
will initiate. After the 8-minute count, the inverter
will attempt to start the compressor again. If the
compressor starts, normal operation will resume.
If the compressor fails to start, this process will be
repeated. Removing power to the unit will reset
the inverter count. When power is restored, the
inverter will attempt to start the compressor within
approximately 8 minutes.
The inverter has a built-in circuit protection to
guard against damage from a failed or shorted
compressor. However, if a failed compressor is
diagnosed, order a new compressor and inverter.
If the compressor fails to start after replacement,
replace the inverter.
Main Control Board
The main control board is positioned behind 2 tabs
at the bottom and attached to the recess with a
lock tab at the top. The board is connected to the
refrigerator with 15 wire harnesses. To remove the
board, unplug the refrigerator, disconnect the wire
harnesses, and push up the lock tab.
Tab
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Lock Tab
Tab