
Page 73
31-5000751 Rev. 0
GF= Gas Furnace, AH=Air Handler, ID=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OD=Outdoor Unit (AC or HP), ZA=Zone system and TS=Thermostat
Alert
Code
Inverter
Code
Inverter Flash
Code
Priority
Condition
Actual Displayed
Alert Text
Component or System Operational State and Troubleshooting
Tip
How to Clear Alert
Code
Red
LED
Green
LED
N/A
N/A
ON
OFF
N/A
NS18HM36 only: Indicates inverter is operating normally.
N/A
N/A
ON
ON
N/A
NS18HM60 only: Indicates inverter is operating normally.
N/A
N/A
OFF
OFF
N/A
Indicates inverter is NOT energized.
423
40
4
flashes
OFF
Service Soon/
Service
Urgent
OD Inverter CT
Circuit Fault
The inverter has detected a circuit issue.
•
When this condition is detected the outdoor control will stop outdoor
unit operations and start the anti-short cycle timer – moderate
condition.
•
Outdoor control will lockout unit after 10 strikes within an hour –
critical condition.
•
Inverter LEDs will flash code 40
•
Refer to the unit service documentation for troubleshooting
procedures.
Inverter flash code 40:
The sequence is:
Red LED: Four Flashes
Green LED: Off
NOTE:
Inverter normal operations with no error code present is as
follows. Red LED is ON and Green LED is OFF.
A moderate alert
code will clear
automatically when
the inverter detects
the condition no
longer exist and will
send a clear alert
code message.
To clear critical alert
code disconnect
power to outdoor unit
and restart.
426
Service
Urgent
OD Excessive
Inverter Alarms
After 10 faults within 60 consecutive minutes, the control will lockout.
Inverter will flash codes 12 to 14 and 53.
NOTE:
These inverter codes do not count towards this lockout
condition.
To clear disconnect
power to outdoor
control and restart.
427
21
2
flashes
1 flash
Service Soon/
Service
Urgent
OD Inverter DC
Peak Fault
The inverter has detected a DC peak fault condition.
•
If condition (55A or higher) is detected, outdoor unit will stop
(compressor and fan) – moderate condition.
•
Anti-short cycle is initiated.
•
If peak current (55A or higher) occurs 10 times within an hour,
system will lockout – critical condition.
•
Inverter LEDs will flash code 21.
•
If the unit is a variable capacity heat pump, this error may occur
entering or exiting a defrost cycle as the compressor restarts after
the 30 second compressor shift delay. If the unit was manufactured
prior to serial number 5817F and has frequent alert code 427, then
compare the inverter part number to the latest part number listed
in the unit repair parts. Units produced after serial number 5817F
which is listed on the unit name plate have an inverter with updated
software that includes compressor current slope logic to reduce the
potential of alert code 427 instances from occurring during defrost.
Replace the inverter with the latest inverter if necessary.
•
Refer to the unit service documentation for detailed troubleshooting
procedures.
NOTE:
Serial number format on unit name plate is PPYYMNNNNN
(PP = Manufacturing Plant, YY and M represents the year
and month made.
Inverter flash code 21.
The sequence is:
•
Red LED: Two Flashes
•
Green LED: One Flash
NOTE:
Inverter normal operations with no error code present is as
follows. Red LED is ON and Green LED is OFF.
To clear, disconnect
and reconnect power
to outdoor control.
Table 24. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes