Page 76
XP25
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
®
thermostat.
Alert
Codes
Priority
Alarm Description
Possible Causes and Clearing Alarm
E 105
Moderate
The outdoor control has lost com
munication with either the thermo
stat or indoor unit.
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.
E 120
Moderate
There is a delay in the outdoor unit
responding to the system.
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
E 124
Critical
The iComfort WiFi
®
thermostat has
lost communication with the out
door unit
for more than 3 minutes.
Equipment lost communication with the thermostat. Check the wiring connections,
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.
E 125
Critical
There is a hardware problem with
the outdoor control.
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.
E 131
Critical
The outdoor unit control parameters
are corrupted
Reconfigure the system. Replace the control if heating or cooling is not available
E 132
Critical
Internal software error.
Replace outdoor control.
Unit Sensor Operations, Checkout and Status / Error Codes
OPERATION
Coil Temperature Sensor (RT21)
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 Temperature Sensor (RT13)
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 Temperature Sensor (RT36)
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.
