Unit Sensor Operations, Checkout And Status / Error Codes - Lennox XC25-024-230-01 Installation And Service Procedure

ERROR CODES:
Table 14. 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 outdoor
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
There is no sensor located on positions 5 and 6 of the connector. A resistor installed between pins 5 and 6 on the cable
harness provides continuity for this circuit. This resistor (location shown in figure 51) provides resistance value between
314669 and 3779 ohms If the resistor becomes damaged or lost, the outdoor control generates a false error code indicating
.
the coil temperature sensor is out of range or faulty (see table 15 on page 65). If resistor is damaged or missing, order re­
placement harness assembly (101334-05).
Ambient temperatures, as read by the ambient temperature sensor (shown in figure 51) 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 15 on page 65). 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 table15 on page 65). The outdoor control uses the liquid line sensor to change the fan speed, allowing
cooling operation at lowered ambient temperatures.
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 separated
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 thermostat.
Check all wiring connections. Cleared after unresponsive device responds to any in­
quiry.
Equipment lost communication with the thermostat. Check the wiring connections, ohm
®
thermostat has
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.
Pins 5 and 6 (No Sensor)
Ambient Temperature Sensor (RT13)
Liquid Line Temperature Sensor (RT36)
Possible Causes and Clearing Alarm
63
®
thermostat.
XC25