Lennox Communicating Systems

This is a minor alert indicating the compressor is slowing down due to high current or approaching temperature limits. It's often informational and occurs during startup. The system automatically adjusts compressor speed and ramp-up speed.

The inverter has detected a DC peak fault. This can cause the outdoor unit to stop. If the peak current condition occurs 10 times within an hour, the system will lock out. The inverter LEDs will flash code 21 (Red: Two Flashes, Green: One Flash).

The compressor is failing to start correctly. The system will stop the compressor and fan. If this happens 10 times within an hour, the system will lock out.

The compressor is drawing too much electrical current. The system tries to reduce the current, but if it stays too high, the outdoor unit will stop. This can happen during startup and may lead to a system lockout if it occurs frequently.

This critical alert indicates a problem with the Y1 relay on the Integrated Furnace Control (IFC), suggesting a possible relay failure.

This critical alert means the O relay on a system component has failed. Either the pilot relay contacts did not close or the relay coil did not energize.

This critical alert indicates that the heat pump configuration jumper has not been cut on the air handler control. This is typically seen when matching a non-communicating heat pump with a Lennox communicating indoor unit.

This critical alert occurs when the Lennox communicating thermostat requests compressor demand (Y1) but the indoor unit control does not detect 24VAC between Y1 and C terminals. This suggests a Y1 relay failure on the system component.

The system has detected a failure with the Y2 relay, which is responsible for sending a compressor demand. This means the indoor control cannot relay the demand to the outdoor unit.

This code appears in non-communicating mode and indicates the jumper between O and R on the furnace has been removed, potentially causing low voltage or a brownout condition.

A communicating device in the system has been disabled due to a fault. The thermostat may have asked for heating or cooling, but received no response from the unit, or it asked to stop but the unit did not respond.

The air handler's electric heat is either not configured or has been configured incorrectly. This can happen when there is a call for heat but the electric heat stages are not set up properly.

There is an issue with the first stage of the air handler's electric heat. This could mean the pilot relay contacts did not close or the relay coil in the electric heat section did not energize.

This alert indicates a problem with the second stage of the air handler's electric heat. The pilot relay contacts may not have closed, or the relay coil might not have energized.

A problem with the third stage of the air handler's electric heat has been detected. This could be due to the pilot relay contacts not closing or the relay coil not energizing.

The system has been heating for at least 15 minutes without a demand for heating. This is displayed on the thermostat's HD display.

The system has been cooling for at least 15 minutes without a demand for cooling. This message appears on the thermostat's HD display.

This critical alert occurs after 10 inverter alarms within 60 consecutive minutes, causing the control to lock out. The inverter will flash codes 12 to 14 and 53.

The outdoor unit's inverter has detected a low DC link voltage. If this condition occurs repeatedly, the system will lock out. The inverter LEDs will flash code 23 (Red: Two Flashes, Green: Three Flashes).

The compressor is unable to start. Both the compressor and fan will stop. If this occurs frequently within an hour, the entire system will lock out.

The inverter's power factor correction circuit has detected an over-current. This causes the compressor and fan to stop. Frequent occurrences will lead to a system lockout.

The outdoor unit's inverter has detected a high DC link voltage, exceeding 480 VDC. If this condition occurs frequently, the system will lock out. The inverter LEDs will flash code 28 (Red: Two Flashes, Green: Eight Flashes).

The compressor is drawing too much electrical current. The system will stop the compressor and fan. If this condition happens multiple times within an hour, the system will lock out.

Communication between the outdoor control and the inverter has been lost. The compressor will stop, and the indoor blower will not run. A critical condition occurs if this happens repeatedly.

An internal error has been detected within the inverter's memory (EEPROM). The system will attempt to reset the inverter by cycling its power. If the problem continues, the outdoor unit will stop operation.

The inverter's heat sink has become too hot. The system will stop the compressor and fan to prevent damage. If this happens five times within an hour, the system will lock out.

The temperature sensor for the inverter's heat sink has failed, reporting extreme temperatures. This will cause the outdoor unit to stop. Repeated faults can lead to a system lockout.

The inverter's power factor correction circuit is experiencing an over-current. This could be caused by high system pressures or a problem with the outdoor fan. The system will attempt to recover, but repeated errors will cause a lockout.

The compressor speed is slowing down due to a high heat sink temperature. The inverter LEDs will flash code 13 (Red: One Flash, Green: Three Flashes). This is often a normal operation during high outdoor temperatures.

The outdoor unit is locked out because the compressor top cap switch has opened five times within one hour. This is due to the compressor's thermal protection sensor repeatedly opening.

The outdoor control has lost communication with the inverter. The compressor demands will stop, and the indoor blower will also stop functioning. This can happen if power is not cycled correctly during service.

An internal error has been detected within the inverter. The system will try to clear this by cycling power to the inverter. If the error persists, the outdoor unit will lock out.

The temperature inside the inverter's heat sink has exceeded its safe limit. The system will slow down to cool it, and if unsuccessful, the compressor and fan will stop. This can lead to a system lockout if it occurs repeatedly.

The sensor monitoring the inverter's heat sink temperature is not working correctly. It's reporting temperatures outside the normal operating range. The outdoor unit will stop the compressor and fan.

The power factor correction (PFC) circuit in the inverter has detected an over-current condition. This might be due to high system pressure or a fan issue. The system will attempt to reset after a few minutes. If it happens too often, the system will lock out.

A blinking amber light on the System Status LED indicates a problem with the Wi-Fi connection. This could mean Wi-Fi is not connected, no network is in range, or there might be a hardware issue.

A blinking cyan light on the System Status LED indicates an internal communication error within the system's hardware.

Double horizontal lines shown on the seven-segment display of an air handler, integrated furnace, or outdoor control indicate that the control has been put into a soft disable mode. This usually happens when the system detects an unknown or unconfigured device.

A blinking green light on the Commissioning Status LED means the commissioning button has been pressed, and the smart hub is now waiting for a connection from a mobile device.

On an iHarmony damper control module or EIM, a blinking green LED (3 seconds on, 1 second off) indicates the device is in soft disable mode, likely due to configuration or communication issues.

A blinking magenta light on the System Status LED means the thermostat's display or mag-mount might not be properly connected.