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XP17
Table 13. Seven-Segment Display Alert Codes (continued)
Alert
Codes
Alarm Description Possible Causes and Clearing Alarm
E 414
The discharge line temperature is high
er than the recommended upper limit of
279ºF.
Discharge line temperature is > 279ºF. Confirm that the system is properly charged with refrigerant.
Check system operating pressures and compare to unit charging charts in installation manual.
Confirm that the outdoor unit is clean. The alarm clears after the discharge temperature is < 225ºF.
E 415
The discharge line temperature has
been consistently higher than the rec
ommended upper limit of 279ºF.
Discharge line high temperature error count reached 5 strikes. Confirm that the system is properly
charged with refrigerant. Check system operating pressures and compare to unit charging charts
in installation manual. Confirm that the outdoor unit is clean. The alarm clears after the discharge
temperature is < 225ºF. The alarm clears after a power reset.
E 416
The outdoor coil sensor is either open,
short-circuited or the temperature is out
of sensor range. As a result the outdoor
unit control will not perform any defrost
tempering.
Coil sensor being detected open or shorted, or temperature is out of coil sensor range. Outdoor unit
control will not perform demand or time/temperature defrost operation. System will still heat or cool.
Check the resistance of the coil sensor and compare to temperature resistance chart. Replace coil
sensor if needed. The alarm clears when outdoor unit control detects proper coil sensor readings or
after a power reset.
E 417
The outdoor unit discharge sensor is ei
ther open, short-circuited or the tem
perature is out of sensor range. As a re
sult the outdoor unit control will not per
form any defrost tempering.
Outdoor unit control detects open or shorted discharge sensor, or temperature that is out of
discharge sensor range. Check the resistance of the discharge sensor and compare to
temperature resistance chart - replace if needed. Reset by replacing the discharge sensor. This
fault is detected by allowing the unit to run for 90 seconds before checking discharge sensor
resistance. If the discharge sensor resistance is not within range after 90 seconds, the board will
count one fault. After 5 faults, the board will lock out. Check for proper sensor reading and
attachment to line. The alarm clears after a power reset.
E 418 There is a faulty W output circuit.
W terminal is energized while in cooling mode. Possible cause may be a stuck closed relay on the
control, or something external to the control that is energizing W terminal when it should not be
energized. Solution: Disconnect any wiring from the W terminal. If 24 volts is still on the terminal,
then it is a stuck relay. If the 24 volts disappears, then there is a need to check any of the wires
hooked up to the W terminal.
E 419
The W output on the outdoor unit has re
ported more than 5 errors. As a result,
the system has shutdown the outdoor
unit.
The W output (code E418) on the outdoor unit has reported more than 5strikes. As a result, the
system has shutdown the outdoor unit. Disconnect thermostat lines from W and verify 24VAC on
the W. If 24VAC is present, replace the control.
E 420
The heat pump defrost cycle has taken
more than 20 minutes to complete.
Defrost cycle lasts longer than 20 minutes. This alarm is applicable with non-communicating heat
pump system only. Check heat pump defrost operation. The alarm is cleared after the ”W1” signal is
removed.
E 421
The W output terminal on the outdoor
unit is not wired correctly.
Voltage sensed on W and O when Y1 thermostat input is deactivated. Another device or wiring fault
is energizing W Check wiring. The alarm clears when wiring is corrected or after a power reset.
NOTE — Additional codes may be found in iComfortt-enabled thermostat manual.
Table 14. Outdoor Control Seven-Segment Unit Status Displays
Description Example of Display
Power up / Reset: Unit type and number of stages is displayed.
Verify configuration with information published on the unit name
plate. If the information is incorrect, refer to flow chart Manually
Configuration of Unit Type to re-configure control.
1 Stage AC: 1AC
2 Stage AC: 2AC
1 Stage AC: 1HP
1 Stage AC: 2HP
POWER-UP 7-SEGMENT DISPLAY STRING
Unit Type / Stages
No Capacity No Fan Profile
Power up / Reset following display of self-dis
covered configuration: Unit nominal capacity is
displayed, if not programmed then three horizontal
lines and the decimal point are displayed for 2 sec
onds.
POWER-UP 7-SEGMENT DISPLAY STRING
Unit Type / Stages
Capacity No Fan Profile
Power up nominal capacity display of an XP21-036: 36
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