The Lennox Conservator III G16 is an older-model furnace that is not currently in production by the Lennox Corporation. The furnace is gas-powered and has an automatic ignition system. Regular filter inspection and cleaning is recommended to help the furnace operate well during the heating season, but there are additional steps that can be taken to troubleshoot issues that may arise with the furnace.
Replace or reset the circuit breaker or fuse if there has been a power failure and the furnace does not have electrical power. Open the gas valve if the gas valve was recently closed and was not opened again prior to trying to operate the Lennox furnace.
Restart the Lennox G16 furnace if power was recently restored or the ignition has gone out as a result of recent power loss. Move the house thermostat to the lowest setting and then switch off the furnace power. Open the burner access panel and adjust the knob on the gas valve to "Off." Allow five minutes to pass so that gas can clear the lines, and proceed if no gas is smelled after five minutes. Adjust the knob on the gas valve back to "On," and replace the burner access panel. Turn on the furnace power and move the thermostat back to the desired temperature.
Observe the pilot light flame once the Lennox furnace is ignited and rotate the adjustment screw on the gas valve slightly in a clockwise direction if the flame is low and does not meet both sides of the thermocouple when lit. The thermocouple is the bracket that surrounds the pilot light. Turn the adjustment screw slightly in a counterclockwise direction if the flame is high or uneven.
Turn off the furnace power and allow the furnace to cool down if you hear loud noises during operation. Check the vent pipe and cap on the exterior of the furnace as well as the heat exchanger, pilot and burners inside the access panel for debris that may be blocking airflow. Use a long-handled brush to clear away any obstructions, such as lint or a buildup of dirt, and then close the access panel and restore furnace power.
Check the thermostat if the furnace is not running or heating the home. Turn up the thermostat past the current air temperature and set the primary switch to "Heat" with the function switch at "Auto" or "On."