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EN
Faults and Error Messages
Universal Air Conditioning Unit
11 Faults and Error Messages
To protect the equipment, certain fault conditions
trigger a shutdown, and the system will not restart until
the fault is repaired.
If an operational failure occurs, the display will flash a
fault or error code message. Fault code displays are
canceled by pressing the mode button.
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This system is equipped with the high-pressure and
low-pressure switches to enable the high- and low-
pressure shutdown to operate.
11 .1 High-Pressure Shutdown
(HI/PS)
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This function is only applicable in AC mode.
The high-pressure switch is monitored by the unity
control board. The high-pressure switch opens when the
discharge pressure rises above a preset maximum limit. If
the high-pressure switch opens, the unity control board
will attempt three restarts and will have a five-minute
countdown between restarts before it shuts down the
entire system. The Q3 control will alternately flash “HI”
and “PS.” This is a sustained shutdown, and even when
the pressure lowers after the shutdown, the system will
remain off until it is reset by pressing the mode button on
the Q3 control.
11 .2 Low-Pressure Shutdown
(LO/PS)
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This function is only applicable in AC mode.
The low-pressure switch is monitored by the unity
control board. The low-pressure switch opens when the
suction pressure drops below a preset minimum limit.
If the low-pressure switch opens, the unit will first run
for two minutes and then shut down for 50 seconds.
This will happen four times. If the switch has not closed,
the unit will shut down for 15 minutes, and the display
will alternately flash “LO” and “PS.” After 15 minutes of
shutdown, the cycle starts again, and the unit will run for
two minutes and then shut down for 50 seconds. This
will repeat four more times.
If after eight attempted compressor starts, the low-
pressure switch does not stay closed, the unit will go
into a sustained shutdown and the Q3 control alternates
flashing “LO” and “PS”.
If the low-pressure switch closes at any time before the
sustained shutdown, the unit will operate normally.
11 .3 Low-Voltage Shutdown
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This function is only applicable in AC mode.
The low-voltage protection feature is always active. If
the AC line voltage drops and remains below the limit
(90 VAC for a 100 VAC system, 100 VAC for a 115 VAC
system) for more than three minutes, the Q3 control
shuts down the entire system. The Q3 control alternates
flashing “LO” and “AC”. This is a sustained shutdown,
and the system will not resume operation even if the
line voltage returns to normal levels. To reset, press the
mode button.
For the low-voltage shutdown function to work properly,
the unity control board internal voltmeter should be
calibrated. This should be done when the system is
installed.
