Outdoor Control 7-Segment Display Alert Codes - Outdoor Control Errors; Unit Sensor Operations, Checkout And Status / Error Codes; Coil Temperature Sensor (Rt21); Ambient Temperature Sensor (Rt13), Liquid Line Temperature Sensor (Rt36) - Lennox XP25-024-230-01 Installation And Service Procedure

ERROR CODES:
Table 17. Outdoor Control 7-Segment Display Alert Codes - Outdoor Control Errors
NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi
Alert
Priority
Codes
The outdoor control has lost com­
E 105 Moderate munication with either the thermo­
stat or indoor unit.
There is a delay in the outdoor unit
E 120 Moderate
responding to the system.
The iComfort Wi­Fi
E 124 Critical lost communication with the out­
door unit for more than 3 minutes.
There is a hardware problem with
E 125 Critical
the outdoor control.
The outdoor unit control parameters
E 131 Critical
are corrupted
E 132 Critical Internal software error.

Unit Sensor Operations, Checkout and Status / Error Codes

OPERATION
Coil temperatures, as read by the sensor (shown in figure 59), which are below -35°F (-37°C) or above 120°F (48°C) trigger a
fault condition. If the defrost coil sensor is open, shorted, or out of the temperature range, the outdoor control will not perform
defrost operation (demand or time/temperature) and displays the appropriate fault code (see table 19 on page 79). Heating
and cooling operation is allowed during this fault condition.
Ambient temperatures, as read by the ambient temperature sensor (shown in figure 59), which are below -35°F (-37°C) or
above 120°F (48°C) trigger a fault condition. If the ambient sensor is open, shorted, or out of the temperature range of the
sensor, the control does not perform demand defrost operation. The control reverts to time/temperature defrost operation and
displays the appropriate alert code (see table 19 on page 79). Heating and cooling operation is allowed in this fault condition.
Liquid line temperatures below -40°F (-40°C) or above 140°F (60°C) trigger a fault condition and result in the appropriate
alarm code (see table 19 on page 79). The outdoor control uses the liquid line sensor to change the fan speed, allowing cooling
operation at lowered ambient temperatures.
®
thermostat.
Alarm Description
Equipment is unable to communicate. Indicates numerous message errors. In most
cases errors are related to electrical noise. Make sure high voltage power is separ­
ated from RSBus. Check for mis­wired and/or loose connections between the stat,
indoor unit and outdoor unit. Check for a high voltage source of noise close to the
system. Fault clears after communication is restored.
Typically, this alarm/code does not cause any issues and will clear on its own. The
alarm / code is usually caused by a delay in the outdoor unit responding to the ther­
mostat. Check all wiring connections. Cleared after unresponsive device responds to
any inquiry
Equipment lost communication with the thermostat. Check the wiring connections,
®
thermostat has
ohm wires and cycle power. The alarm stops all associated HVAC operations and
waits for a heartbeat message from the unit that's not communicating. The alarm /
fault clears after communication is re­established.
There is a control hardware problem. Replace the outdoor control if the problem pre­
vents operation and is persistent. The alarm / fault is cleared 300 seconds after the
fault recovers.
Reconfigure the system. Replace the control if heating or cooling is not available
Replace outdoor control.

Coil Temperature Sensor (RT21)

Ambient Temperature Sensor (RT13)
Liquid Line Temperature Sensor (RT36)
Possible Causes and Clearing Alarm
Page 76
XP25