Fujitsu FO20R Series Installation Instructions Manual page 56

9.0 DIAGNOSTICS & TROUBLESHOOTING
9.5 Active Protection Fault Details (cont.)
16 – HP Sensor Not Configured – T926_O
If the inverter is not configured or does not hold
the configuration for the high pressure switch in the
Modbus register, the inverter will provide this fault.
L16 – Brown Out Fault – A959_O Brown Out
Fault
If the inverter detects input AC voltage < 155VAC
for 4 seconds the VSODC will automatically shut
the compressor off and keep it from operation. The
VSODC will leave the compressor off until the input
AC voltage increases to >175VAC for 4 seconds.
At this time the VSODC will restart the compressor.
While the compressor is off the VSODC will display
a 16 on the dual 7-segment LEDs.
IMPORTANT: This mode of active protection is
automatically reset.
L21 – Low Pressure Refrigerant – A/T 021_0
Low Refrigerant Pressure
• The VSODC will display a flashing "21" followed
by a flashing "L" when a low-pressure control
lockout occurs.
Active Protection – Code
21L – Open low-pressure
control
IMPORTANT:
protection must be manually reset.
• The VSODC addresses low-pressure control
faults differently depending on the mode of unit
operation (cooling or heating mode).
Cooling Mode
• If the LPC opens three (3) times during the same
call for cooling operation, the VSODC will lock
out the compressor to keep it from continuing to
operate and flash a "21" on the dual 7-segment
LEDs followed by an "L."
56
This mode of active
Active Protection – Code
21L – Open low-pressure
control
IMPORTANT:
protection must be manually reset.
Heating Mode
• There are two scenarios that will cause active
protection during an LPC trip when the unit is in
the heating mode:
Active Protection With Hard Lockout:
• If the LPC opens three (3) times within 120
minutes for the same call for heating operation,
the VSODC will lock out the compressor to
keep it from continuing to operate and flash an
"21" on the dual 7-segment LEDs followed by a
"L."
Active Protection – Code
21L – Open low-pressure
control
IMPORTANT:
protection must be manually reset.
Active Protection With Soft Lockout:
• If the LPC opens three (3) times for the same
call for heating and the outdoor ambient
temperature is below -10°F [-23°C], the VSODC
will lock out the compressor to keep it from
continuing to operate and flash a "21" on the
dual 7-segment LEDs followed by an "L."
Once the outdoor ambient rises above -10°F
[-23°C], the VSODC will clear active protection
automatically.
IMPORTANT:
protection will automatically deactivate once the
outdoor temperature rises above -10°F [-23°C].
Wait until the outdoor ambient temperature rises
above -10°F [-23°C] before performing further
diagnostics.
27- AC Input Under Voltage – A907_O_Inverter
Fault
If the inverter detects input AC under voltage the
VSODC will automatically shut the compressor off
and keep it from operation. The VSODC will leave
the compressor off until the input AC voltage
This mode of active
This mode of active
This mode of active