Honeywell RTHL2510 ユーザーズマニュアル

If you have difficulty with your thermostat, please try the following suggestions.  
Most problems can be corrected quickly and easily.

•  Make sure furnace door is closed securely.
•  Make sure fresh AAA alkaline batteries are correctly installed (see

page 17).

•  Set system switch to Heat (see page 7). Make sure the temperature is 

set higher than the Inside temperature.

•  Set system switch to Cool (see page 7). Make sure the temperature is 

set lower than the Inside temperature.

•  Wait 5 minutes for the system to respond.