Lennox Unit controller Error Code 123

• High output voltage on T1 transformer. Alarm set when 24VAC voltage high if calculated RMS voltage is below low voltage alarm threshold for more than two seconds. System will stop unit operations (cooling, heating and ventilation). Low voltage threshold is 30VAC. • The CORE Unit Controller will clear alarm 24VAC Voltage high if calculated RMS voltage is above High Voltage Alarm Threshold + 1 VAC for more than two seconds. After the HIGH 24VAC alarm has been cleared, the CORE Unit Controller will ignore all service demands until the Error Time Off Delay has expired.