Thermostat shows random characters or garbled display

Safety first: Turn off power to the HVAC system before removing the thermostat.

• Step 1 – Power cycle: Turn off the furnace/air handler breaker for 2–3 minutes, then restore power.
• Step 2 – Factory reset: If you can still navigate menus, perform a factory reset to reload default settings.
• Step 3 – Inspect for moisture: Remove the thermostat and check for condensation or water damage. Allow to dry thoroughly if moisture is present.
• Step 4 – Replace thermostat: If the display remains garbled, the internal electronics are damaged and the thermostat must be replaced.

When to call a professional: For surge-related damage, also have an electrician check home grounding and surge protection.