Covers How to Unlock Honeywell RTH9580WF Thermostat. Now Many Honeywell home thermostats have a screen lo mode. This keeps anyone from changing thermostat settings without first entering a password. First, you set this pass code when locking your t-stat. Then, to unlock it, the t-stat asks you to enter this secret code. This then grants … Continue reading How to Unlock Honeywell RTH9580WF Thermostat