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Flash Code
Type
Amber LED Description
DISCHARGE TEMP OUT
System
74
(Elevated from fault code
Malfunction
MAXIMUM POWER MODE
--- TEMP (Temporary RPM
75
Local
reduction or stage lowering
FAN INVERTER LOCKOUT
System
(Elevated from fault code
76
Malfunction
MAXIMUM POWER MODE
77
Local
(Temporary RPM reduction
or stage lowering will re-
Reset
Time
OF RANGE LOCKOUT
2 Hours
59 after 5 occurrences)
NA
will result)
2 Hours
61 after 5 occurrences)
--- COMP CURRENT
NA
sult)
Mode
Possible Causes
High Load condi-
Cool
tions
Low Charge or Loss
Check charge in heating mode per heating
of Charge at low am-
Heat
bient heating condi-
match then pull out charge, weigh in using
tions
Expansion Device
Heat
Restriction
Sensor Harness not
connected to AOC
control
Broken or loose har-
ness wire
Broken or Damaged
Sensor
Both
Indoor Unit Airflow
too low or off
Outdoor Unit Airflow
Troubleshoot outdoor fan motor and make
too low or off
Reversing Valve By-
pass or Reversing
Valve not energized
Hardware damage to
Both
AOC control
Nuisance fault dur-
Both
ing non ---operational
mode
Indoor Airflow too
Heat
low or off
Outdoor Airflow too
low or off
Both
Blocked Inverter
Heat Exchanger
(fins)
Application violates
guideline
Fan blade bent/out
of balance
Fan blade restricted
Both
Fan motor wiring
Fan motor
Inverter damage
charge status, if high remove charge using
Cool
Overcharged System
Check charge in heating mode per heating
Heat
Overcharged System
match then pull out charge, weigh in using
Compressor is oper-
ating outside the al-
lowed operational
envelope
Incorrect refrigerant
charge
Both
Outdoor Airflow too
low or off
Incoming power sup-
ply voltage
Loose or incorrect
wire connections
22
Actions
Over charge: Check system charge
check charge chart. If pressures do not
heating charge method
Heating: Trouble shoot EXV (coil, harness-
es); Trouble shoot the TXV
Power Cycle system, is EXV moving on
power up (audible)
Ensure plug is connected to AOC control
Check harness for continuity; see resis-
tance chart to check resistance at given
temperature
Check harness for continuity; see resis-
tance chart to check resistance at given
temperature
Troubleshoot indoor fan motor and make
sure it is working
sure it is working
Reversing Valve stuck halfway
Ensure AOC fuse is good
24 VDC in cooling mode
Check harness and connectors
Replace AOC control
Refer to TIC 2015 ---0017 for more details
Check indoor airflow
Check ODU coil for clogging (ice or de-
bris) and clean if necessary; Troubleshoot
ODU fan motor and make sure it is work-
ing
Check Inverter fins for debris and clean if
necessary
Consult Application Guideline for compli-
ance
Check outdoor fan blade
Check for ice build up
Check outdoor fan blade clearance
Check for ice build up
Check outdoor fan motor connectors and
harness
Replace outdoor fan motor
Replace inverter
Check system subcooling to determine
Charging Mode (follow proper charging
procedures)
check charge chart. If pressures do not
heating charge method
Inverter will reduce speed to a lower stage
Check refrigerant amount
Check ODU coil for clogging (ice or de-
bris) and clean if necessary; Troubleshoot
ODU fan motor and make sure it is work-
ing
Check voltage versus unit rating plate for
allowable range
Check incoming power leads and leads to
the compressor plug
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