22
Flash Code ActionsPo ssible CausesMode
Reset
Time
Amber LED DescriptionTy pe
74
System
Malfunction
DISCHARGE TEMP OUT
OF RANGE LOCKOUT
(Elevated from fault code
59 after 5 occurrences)
2Hours
Cool
High Load condi-
tions
Over charge: Check system charge
Heat
Low Charge or Loss
of Charge at low am-
bient heating condi-
tions
Check charge in heating mode per heating
check charge chart. If pressures do not
match then pull out charge, weigh in using
heating charge method
Heat
Expansion Device
Restriction
Heating: Tr ou ble shoot EXV ( coil, harness-
es); Trouble shoot the TXV
Power Cycle system, is EXV moving on
power up (audible)
Both
Sensor Harness not
connected to AOC
control
Ensure plug is connected to AOC control
Broken or loose har-
ness 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
Indoor Unit Airflow
too low or off
Troubleshoot indoor fa n motor and make
sure it is working
Outdoor Unit Air f l ow
too low or off
Troubleshoot outdoor fan motor and make
sure it is working
Reversing Valve By-
pass or Reversing
Valve not energized
Reversin g Valve stuck halfway
Ensure AOC fuse is good
24 VDC in cooling mode
Check harness and connectors
Both
Hardware damage to
AOC control
Replace AOC control
Both
Nuisance fault dur-
ing n on ---operational
mode
Refer to TIC 2015---0017 for more details
75 Local
MAXIMUM POWER MODE
--- TEMP (Temporary RPM
reduction or stage lowering
will result)
NA
Heat
Indoor Airflow too
low or off
Check indoor airflow
Both
Outdoor Airflow too
low or off
Check ODU coil for clogging (ice or de-
bris) and clean if necessary; Troubleshoot
ODU fan motor an d make sure it is work-
ing
Blocked Inverter
Heat E xchanger
(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 ou tdoor fan motor
Inverter damage Replace inverter
77 Local
MAXIMUM POWER MODE
--- COMP CURRENT
(Temporary RPM reduction
or stage lowering will re-
sult)
NA
Cool Overcharged System
Check system subcooling to determine
charge status, if high remove charge using
Charging Mode (follow proper charging
procedures)
Heat Overcharged System
Check charge in heating mode per heating
check charge chart. If pressures do not
match then pull out charge, weigh in using
heating charge method
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 necessary; Troubleshoot
ODU fan motor an d make sure it is work-
ing
Incoming power sup-
ply voltage
Check voltage versus unit rating plate for
allowable range
Loose or incorrect
wire connections
Check incoming power l eads and leads to
the compressor plug
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