Your temperature setting is likely outside the allowed range. The thermostat has hard limits.
- For Heat mode, the allowable range is 40°F to 90°F (4.5°C to 32.0°C).
- For Cool mode, the allowable range is 50°F to 99°F (10.0°C to 37.0°C).
First, check your current mode and desired temperature.
- Press Menu > System > Mode to see if you're in Heat or Cool.
- If you're in Heat and trying to set below 40°F, it won't accept it. Set a temperature within the 40-90°F band.
- If you're in Cool and trying to set above 99°F, it won't accept it. Set a temperature within the 50-99°F band.
IF THAT DIDN'T WORK: The screen might be unresponsive. Press the center area of the displayed temperature to wake the screen fully, then try the arrows again.