Thermostat frequently overshoots or undershoots the set temperature; room feels too hot or too cold compared to the setpoint.

Safety first: No hazardous work is required; do not open live electrical panels.

• Check thermostat location: Ensure it is on an interior wall away from direct sunlight, drafts, exterior doors, and heat‑producing appliances.
• Seal wall opening: Remove the thermostat and seal gaps in the wall box to prevent drafts from behind.
• Adjust settings: In the thermostat's advanced settings, adjust cycle rate, swing, or differential to a tighter value if the system allows.
• Calibrate offset: Compare the thermostat reading with a reliable thermometer and apply a temperature offset in the settings if supported.
• Replace thermostat if unstable: If readings fluctuate wildly or cannot be calibrated, the internal sensor may be defective and the thermostat should be replaced.