Lennox XC21 Series Unit Information page 37

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.
Air Conditioner
Control LEDs
Thermostat Thermostat Thermostat
DS11 DS11 DS14 DS14
Green Green Red Red
On On Not applicable
2 fast
On flashes Not applicable
then pause
1 fast
flashes Off Not applicable
then pause
2 fast
flashes Off Not applicable
then pause
2 fast
flashes On Not applicable
then pause
Moderate Alert
None None
Code 105
Moderate Alert
None None
Code 120
Critical Alert
None None
Code 124
Critical Alert
None None
Code 125
Moderate /
Critical Alert
None None
Code 126
Critical Alert
None None
Code 131
Critical Alert
None None
Code 132
icomfort icomfort icomfort
Toucht Toucht Toucht
Condition Condition Condition
Display Display Display
Air conditioner
control failure
Defrost
First−stage
compressor
cooling
Second−stage
compressor
cooling
Dehumidification
mode
Device
communication
failure
Unresponsive
device
Active subnet
controller missing
Hardware failure
Internal control
communication
failure
Corrupted control
parameters
Failed flash CRC
check.
Possible Possible Possible
Cause(s) Cause(s) Cause(s)
Indicates that control has internal component failure. Cycle 24 volt power to
control. If code does not clear, replace control.
These are codes that show status of operation whether in low stage or high stage,
heating or cooling, defrost or in the EDA mode.
These are codes that show status of operation whether in low stage or high stage,
heating or cooling, defrost or in the EDA mode.
These are codes that show status of operation whether in low stage or high stage,
heating or cooling, defrost or in the EDA mode.
These are codes that show status of operation whether in low stage or high stage,
heating or cooling, defrost or in the EDA mode.
ALERT STATUS
icomfort Toucht thermostat device is unable to communicate with any other
device on the RSBus. Alarm only occurs if a specific device did communicate
initially after power up and communication was later lost. Possible causes are
lost connection, bus short or open, or other device stop responding.
Message could be sent by any device on RSBus if expected response
message is not received from other device. If sent by indoor or outdoor control,
device did not get expected response (incorrect or no response at all) from
active Subnet controller. If sent by the icomfort Toucht thermostat, and did not
get the expected response (incorrect or no response at all) from device.
Normally this indicate device malfunction.
Device lost connection to icomfort Toucht thermostat. Thermostat is sending
heartbeat message in one minute intervals. Device sets this alarm if no
Heartbeat is received for three minutes. Normally this indicate lost connection
to thermostat, or thermostat is not working. Alert will clear after valid subnet
controller message is received.
Entire or partial system failure. Alert will clear 300 seconds after fault has
recovered.
Internal communication on outdoor control. Alert will clear 300 seconds after
fault has recovered.
System stored configuration data is corrupted. System will not run. Refer to
communicating thermostat for memory corrupt handling.
No operations, A175 control enters boot loader mode. Alarm will clears after
reset.
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Solution Solution Solution
XC21