Lennox thermostats troubleshooting

The advanced developments of the Lennox company affect equipment, inter alia, thermostats, as well as systems for their maintenance. In particular, the table of Lennox thermostats troubleshooting is presented below. Everything for service of consumers!

If...Then ...
Key to the right of the screen key is blank.MORE key remains blank unless the Furnace Filter Change Reminder has been turned on. See User Set-Up Number 0500.
Display is blank.Check that fresh AAA alkaline batteries are installed as marked on the thermostat.
Temperature settings do not change.Check that temperature settings are:
• Heating 40°F to 90°F (4.5°C to 32°C).
• Cooling 50°F to 99°F (10°C to 37°C).
Heating system does not turn on.• Set the system to heat by pressing the SYSTEM key.
• Check the heat temperature setting to be sure it is set above the room temperature and "Heat On” is displayed solidly on the screen.
• Check the circuit breaker to make sure it is not tripped.
• Check the power switch at the heating and/or cooling system to make sure it is on.
• Check the furnace door to make sure it is closed securely.
• Wait five minutes for the heating system to respond.
• If the problem has not been identified and corrected, contact a qualified service technician.
Cooling system does not turn on.• Set the system to Cool by pressing the SYSTEM key.
• Check the cool temperature setting to be sure it is set below the room temperature and "Cool On” is displayed solidly on the screen.
• Check the circuit breaker to make sure it is not tripped.
• Check the power switch at the heating and/or cooling system to make sure it is on.
• Check the furnace door to make sure it is closed securely.
• Wait five minutes for the cooling system to respond.
• If the problem has not been identified and corrected, contact a qualified service technician.
Cannot set System setting to Cool.Check Installer Set-Up Number 170: Heating and/or Cooling Type*. Make sure the setting matches the installed heating and/or cooling system.
’’Heat On” is not displayed on the screen.Set the System setting to Heat and set the temperature setting above the room temperature. If “Heat On” is shown solidly in the display, but the heating system does not turn on, see "Heating system does not turn on” suggestions on the previous page.
’’Cool On” is not displayed on the screen.Set the System setting to Cool and set the temperature setting below the room temperature. If “Cool On” is shown solidly in the display, but the cooling system does not turn on, see "Cooling system does not turn on” suggestions at the top of this page.
“Wait” is displayed on the screen.Compressor minimum-off timer is activated. Wait up to five minutes for the compressor to turn on.
Fan does not turn on in a call for heat (electric furnaces only)Check Installer Set-Up 0180: Fan Control in Heating*. Make sure Electric Heat option is selected.
Both heating and cooling systems are operating at the same time.Check Installer Set-Up Number 170: Heating and/or Cooling Type*. Make sure the setting matches the installed heating and/or cooling system. Check to ensure that bare portions of wires are not touching.
Heating is running in Cool mode.Check Installer Set-Up Number 170: Heating and/or Cooling Type*. Make sure the setting matches the installed heating and/or cooling system.
Heating system does not turn off and the heat temperature setting is set below the room temperature (’’Heat On” is not shown in display.)Check Installer Set-Up Number 170: Heating and/or Cooling Type*. Make sure the setting matches the installed heating and/or cooling system.
Red LED is lit in the upper right corner of the thermostat when the system monitor detects a possible problem.A system monitor is wired to the thermostat L terminal. Refer to suggestions given in Heating or Cooling System Does Not Turn On sections in this table.