What is Allergen Defender?
FAQ , Thermostats , Troubleshooting Modified: March 19, 2026
Allergen Defender brings Lennox innovation to cleaner air by monitoring the air quality and pollen levels in your zip code. When high levels of pollutants or allergens are reported, the Lennox S40 Smart Thermostat automatically increases fan speed to create more clean air per hour in your home. You can choose this setting by going to Menu > Settings > Fan > Allergen Defender.
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