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XP21
System fault and lockout LED (DS11 / DS14) alarm codes takes precedence over system status LED codes (cooling, heating stages or
defrost/dehumidification). Only the latest active LED fault or lockout alarm code if present will be displayed. If no fault or lockout codes are active, then
system status LEDs are routinely displayed. See notes 1 and 2 in table below for duration of fast / slow flashes and pause.
Heat Pump Control
LEDs
SolutionPossible Cause(s)Condition
icomfortt
Thermostat
Display
DS11
Green
SolutionPossible Cause(s)Condition
icomfortt
Thermostat
Display
DS14 Red
DS11
Green
SolutionPossible Cause(s)Condition
icomfortt
Thermostat
Display
DS14 Red
Slow flash Off
Moderate
Alert Code
412
High pressure
fault
Unit pressure is above the upper limit. System is shut down. Check system operating
pressures and compare to unit charging charts. Clears when pressure switch closes.
On Off
Critical Alert
Code 413
High pressure
switch lockout
Open high pressure switch error count reached 5 strikes. Check system charge using
approach and subcooling temperatures. Check outdoor fan operation. Check for dirt
or debris blocking air flow to outdoor unit. Reset by putting outdoor unit control in test
mode or resetting low voltage power.
Slow flash On
Moderate
Alert Code
414
High Discharge
line temperature
fault
Discharge line temperature is > 279ºF. Check system operating pressures and
compare to unit charging charts in installation manual. Clears after discharge
temperature is < 225ºF.
Fast flash On
Critical Alert
Code 415
High Discharge
Line Temperature
Strikes Lockout
Discharge line high temperature error count reached 5 strikes. Check system charge
using approach and subcooling temperatures. Reset by putting outdoor board in test
mode or resetting low voltage power.
Fast flash On
Critical Alert
Code 416
Outdoor Coil
Sensor Faulty
Sensor being detected open or shorted, or temperature is out of sensor range.
Outdoor unit control will not perform demand or time/temperature defrost operation.
(System will still heat or cool.) Clears when outdoor unit control detects proper sensor
readings.
Off Fast flash
Moderate /
Critical Alert
Code 417
Discharge sensor
fault
Outdoor unit control detects open or shorted sensor, or temperature that is out of
sensor range. Critical Alert after 10 minutes. Reset by replacing sensor. This fault is
detected by allowing the unit to run for 90 seconds before checking sensor
resistance. If the 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. Replace if out−of−spec.
3 fast
flashes
then pause
Off
Moderate /
Critical Alert
Code 418
W output
hardware fault
When auxiliary heat output is detected as active. Fault in the heat pump control. Re-
place heat pump control. See figure 47 for further details.
3 fast
flashes
then pause
On
Moderate /
Critical Alert
Code 419
W output
hardware fault
lockout
If heat pump control recognizes five output hardware fault events during a single cool-
ing demand, the heat pump control will initiate a lockout. See figure 47 for further
details.
Off
3 fast
flashes
then pause
Critical Alert
Code 421
W external
miswire fault
When auxiliary heat output is detected as active after compressor has been de−en-
ergized. See figure 47 for further details.
Simultaneous fast
flashes then pause
None
Second−stage
heat lock−in
If the unit is in non−communicating mode and it goes to second stage due to ambient
temperature being below second stage lock−in setting (E48).
Fast simultaneous flashing of DS11,
DS13, DS14 and DS15
OEM mode Factory test mode.
1. Pause duration is two (2) seconds.
2. Fast flash duration is 1/2 second. Slow flash duration is one (1) second.
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