81
Table 19. Alert Codes and Troubleshooting
GF= Gas Furnace, AH=Air Handler, ID=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OD=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system and TS=Thermostat
Alert
Code
Inverter
Flash
Code
Priority
Condition
Actual Displayed
Alert Text
Under dealer
control center >
Notifications
Component or System Operational State and Troubleshooting Tip
How to clear alert code
424
Service Soon
OD Liquid Line
Sensor Faulty
The liquid line temperature sensor has malfunctioned.
• In normal operation after outdoor control recognizes sensors, the alert code will be sent if a
valid temperature reading is lost.
• Compare liquid line sensor resistance to temperature / resistance charts in unit installation
instructions.
• Replace sensor pack if necessary.
•
At the beginning of (any) configuration, furnace or air handler control will detect the presence of
the sensor(s).
•
If detected (reading in range), appropriate feature will be set as ‘installed’ and shown in the
thermostat ‘About’ screen.
Automatically clears upon
configuration, or sensing normal
values.
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
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 XP20 or XP25 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.
