Thermostat backlight or display is very dim and hard to read, even in normal lighting

Safety: Turn OFF power to the HVAC system before removing the thermostat if needed.

• Brightness setting: In the thermostat display settings, increase the brightness or backlight level if adjustable.
• Check voltage: Measure R–C voltage at the thermostat. If significantly below 24 VAC, address low-voltage issues (transformer, wiring) first.
• Inspect for damage: Remove the thermostat and look for signs of heat damage or discoloration around the display area.
• Replacement: If brightness remains poor despite proper voltage and settings, the backlight or display driver is failing. Replace the thermostat.