21
Flash Code Ty p e Amber LED Description
Reset
Time
Mode Possible Causes Actions
71 Local
COMPRESSOR DROPPED
OUT
6Min-
utes
Both
MOC is reporting
that compressor
isn’t running
Check compressor winding resistance or
miswire of compressor leads at terminals
U,V,W
72 Local
SUCTION OVER TEMPER-
ATURE EVENT
(elevates to fault code 82
after 3 occurrences)
15 Min-
utes
Both See f au l t 82 Same actions for 82
74
System
Malfunction
DISCHARGE TEMP OUT
OF RANGE LOCKOUT
(Elevated from fault code
59 after 3 occurrences)
2Hours
Both
Sensor Harness not
connected to AOC
control
Ensure plug is connected to AOC control
Broken or loose
harness wire
Check harness for continuity; see resis-
tance chart to check resistance at given
temperature
Broken or Damaged
Sensor
Check harness for continuity; see resis-
tance chart to check resistance at given
temperature
Hardware damage
to AOC control
Replace AOC control
Indoor Unit Airflow
too l ow or off
Tr oubleshoot indoor fan motor and make
sure it is working
Outdoor Un it Airflow
too l ow or off
Tr oubleshoot outdoor fan motor and
make sure it is working
Reversing Valve By-
pass or Reversing
Valve not energized
Reversing Valve stuck halfway
Ensure AOC fuse is good
24 VDC in cooling mode
Check harness and connectors
Cool
High Load condi-
tions
Over charge: Check system charge
Heat
Low Charge or Loss
of Charge at low
ambient heating
conditions
Undercharged or No charge: check
charge
Heat
Expansion Device
Restriction
Heating: Trouble shoot EXV (coil, har-
nesses); Trouble shoot the TXV
Power Cycle system, is EXV moving on
power up (audible)
75 Local
MAXIMUM POWER MODE
--- TEMP (Temporary RPM
reduction or stage lower-
ing will result.)
NA Both
Outdoor Airflow too
low or off
Check ODU coil for clogging (ice or de-
bris) and clean if n ecessary; Tr oubleshoot
ODU fan motor and make sure it is work-
ing
Blocked Inverter
Heat Exchanger
(fins)
Check Inverter fins for debris and clean if
necessary
Application violates
guideline
Consult Application Guideline for compli-
ance
76
System
Malfunction
FAN INVERTER LOCKOUT
(Elevated from fault code
61 after 5 occurrences)
2Hours Both
Fan blade bent/out
of balance
Check outdoor fan blade
Check for ice build up
Fan blade restricted
Check outdoor fan blade clearance
Check for ice build up
Fan motor wiring
Check outdoor fan motor connectors and
harness
Fan motor Replace outdoor fan motor
Inverter damage Replace inverter
77 Local
MAXIMUM POWER MODE
--- COMP CURRENT
(Temporary RPM reduction
or stage lowering will re-
sult.
NA Both
Compressor is oper-
ating outside the al -
lowed operational
envelope
Inverter will reduce speed to a lower
stage
Incorrect refrigerant
charge
Check refrigerant amount
Outdoor Airflow too
low or off
Check ODU coil for clogging (ice or de-
bris) and clean if n ecessary; Tr oubleshoot
ODU fan motor and make sure it is work-
ing
Incoming power
supply voltage
Check voltage versus unit ratin g plate for
allowable range
Loose or incorrect
wire connections
Check incoming power leads and leads
to the compressor plug
79 Local
COMPRES SOR/INVERTER
FAULT
(Elevates to fault code 88
after 3 occurrences)
6Min-
utes
Both
Compressor fails to
start
System will try to self---mitigate with re-
peated start attempts
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