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When checking inverter voltage output, connect
the test-meter leads to any 2 of the 3 compres-
sor lead wires at the inverter plug (plug should
be connected). The same reading should be
measured between any 2 of the 3 wires.
The inverter controls compressor speed by
frequency variation and by Pulse Width Modula-
tion (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) - 57 Hz
• Medium speed (2100 rpm) - 70 Hz
• High speed (3120 rpm) - 104 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 in-
verter (all wires must be connected). The in-
verter 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 4-6 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 8 seconds.
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 in-
verter.
If the compressor fails to start after replacement,
replace the inverter.
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