Thermostat backlight or display is very dim and hard to read

Safety first: Turn off power before removing the thermostat if you will access wiring.

• Step 1 – Adjust brightness: In the display settings, increase the backlight brightness and see if visibility improves.
• Step 2 – Check power: Measure 24 VAC between R and C at the thermostat to ensure proper voltage. Low voltage can dim the display.
• Step 3 – Inspect for damage: Remove the thermostat and check for signs of moisture or heat damage around the display area.
• Step 4 – Replace thermostat: If brightness remains poor even at maximum setting and power is correct, the backlight or display driver has likely degraded and the thermostat should be replaced.