How to Troubleshoot a Lennox HVAC C22-41

Turn the main gas valve on fully in a counterclockwise movement if the Lennox furnace shuts down unexpectedly. Check the vents throughout the home and move any obstructions that may be preventing air flow to or from the furnace. Keep the furnace area clear as well. Reset or replace the fuse or circuit breaker if necessary.

Move the thermostat switch to “Auto” if the supply air fan seems to be running constantly, even when the temperature set point is reached. Readjust the automatic “Off” setting to 90 degrees Fahrenheit if the automatic turn-off point is set below the current ambient temperature. Increase the temperature operating point if set below the current ambient temperature.

Look at the wiring around the furnace if the fan does not run or the unit never shuts off. Contact Lennox for service and disconnect power to the furnace if any of the wiring seems loose or damaged.

Inspect the mounting hardware if there is a strange hissing noise coming from the furnace, specifically around the decoupler box, air intake connection or the air intake pipe. Tighten any loose parts.

Disconnect power and open the furnace access door, then remove the filter from the filter clips if the furnace is not heating accurately or is noisy during use. Wash the filter well with cold water and dishwashing liquid and let it air dry prior to placing it back in the furnace, securing the clips and reconnecting power.

Check the blower wheel inside the access panel if the fan is very loud when the furnace is operating. Disconnect power and clean the wheel with a clean cloth when the furnace is cool to remove debris, then shut the access panel and restore power.

Get the furnace restarted if power is lost by adjusting the thermostat to the lowest setting and turn the gas knob to "Off." Wait 15 minutes in order for gas to clear the line, then smell carefully for gas before proceeding. Turn off the furnace and leave the home if there is the scent of gas and call your gas servicer. Continue if there is no gas smell and turn the gas knob to "On." Close the access panel and connect the furnace power before setting the thermostat to the desired temperature.