Although your Lennox thermostat can help regulate your furnace's temperature and give you a toasty warm feeling, it works only as well as it is maintained. Your Lennox thermostat can run into simple problems related to battery issues and improper settings, so conduct a few troubleshooting steps before calling a repair technician. Solving simple problems related to programmable Lennox thermostats, such as Lennox's Elite series, can maximize energy efficiency and performance.
Remove your Lennox thermostat from the wall if the display is blank. Remove it by pulling it straight out from the wall plate. Open the battery compartment and remove the old AAA alkaline batteries. Insert new batteries, close the compartment, then place your thermostat back on the wall.
Ensure that the heating temperatures are between 40 to 90 degrees Fahrenheit if you are unable to change the temperature settings. Press the "SYSTEM" key to set the system to heat if your heating system is not turning on.
Set the temperature setting above the room's ambient temperature. 70 degrees Fahrenheit or slightly higher is ideal. Make sure "Heat On" is displayed on your thermostat's display.
Check your heater's power switch and make sure your unit is turned on if you are unable to change your thermostat's settings. If you have just turned on your furnace, wait five minutes for the heat system to respond.
Check the furnace door to make sure it is closed properly if the furnace is not turning on. Your thermostat will not regulate temperature if the furnace fails to operate.
Set the system setting to "Heat" if "Heat On" is not displayed on your thermostat's display. Set the heat settings above room temperature. If "Heat On" is displayed but your furnace does not turn on, make sure the ambient temperature of the room is not higher than the thermostat setting. A couple of degrees difference between the thermostat setting and the actual temperature is not uncommon. After you've determined that the room temperature is several degrees lower than the thermostat temperature setting, check your furnace. Make sure it is turned on.
Wait up to five minutes for the compressor to turn on, particularly if you see "Wait" on the display. The compressor minimum-off timer is likely activated and will turn on in a few minutes.