Lennox Error Code 434

Priority condition: Service Soon/Service Urgent • Outdoor control has lost communications with the inverter continuously during a single thermostat call and one hour period. • Outdoor control will stop all compressor demands – moderate condition. • Indoor blower will stop functioning. NOTE: Indoor blower will not run in test mode either when alert code 434 is active. Only after system reset will it operate. • This alert code will occur if the outdoor unit power is turned off and the indoor unit power (24VAC to Lennox outdoor control) remains on, or if the indoor unit power is turned off (24VAC to Lennox outdoor control) and the outdoor unit power is on. This could occur while performing service or maintenance procedures on the indoor or outdoor unit. • The Lennox outdoor control will attempt to re-establish communication to the inverter when the alert code 434 occurs by cycling the outdoor unit contactor off for two minutes. Upon energizing the contactor the Lennox outdoor control will attempt to communicate to the inverter for three minutes. This process will be repeated three times in attempt to establish communication before locking out. • If the unit is locked out with a critical alert code 434, reset the system by cycling the outdoor unit power off and back on. Then cycle the indoor power off (24VAC to the Lennox outdoor control) and then back on. • If this condition continuously occurs during a one hour period and during a single thermostat call, the outdoor unit will lock out and display alert code 434 – critical condition. Troubleshooting Options: • Check for loose or disconnected electrical connections. • Interruption of main power to inverter. • Inverter LEDs will flash code 53. • Refer to the unit service documentation for detailed troubleshooting procedures. Priority condition: Service Soon/Service Urgent Inverter flash code 53. Priority condition: Service Soon/Service Urgent The sequence is: • Red LED: Five Flashes • Green LED: Three Flashes NOTE: Inverter normal operations with no error code present is as follows. Red LED is ON and Green LED is OFF