How do I respond to the air filter reminder alert?

When the alert icon appears, press Menu, navigate to ALRT, and press Select — the message REPL (Replace Air Filter) will appear. Honeywell recommends changing the air filter before clearing the reminder. You can snooze the reminder for 7 days by pressing Select when SNZE appears, or clear it by navigating to CLER and pressing Select. (Page 7)

From the official Honeywell T4 Pro Programmable Thermostat (TH4110U2005/U) manual, page 7

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