33-00066EFS—01  47
Troubleshooting
If you have difficulty with your thermostat, try these suggestions. Most problems can  
be corrected quickly and easily.
Screen is blank  •  Check circuit breaker and reset if necessary.
•  Make sure power switch at heating and cooling system is on.
•  Make sure furnace door is closed securely.
•  If thermostat is battery powered, make sure fresh AA alkaline batteries are 
installed correctly.
Screen is 
difficult to read
•  Change screen brightness using Preferences menu (see page 33).
Red light is on •  If thermostat is in Emergency Heat mode, the red light is normal. It shows 
that the thermostat is in Emergency Heat mode.
•  If thermostat is not in Emergency Heat mode, an alert is active. Check 
message on the thermostat screen.
Heating or 
cooling system 
does not 
respond
•  Touch SYSTEM to set system to Heat. Make sure the temperature is set 
higher than the Inside temperature.
•  Touch SYSTEM to set system to Cool. Make sure the temperature is set  
lower than the Inside temperature.
•  Check circuit breaker and reset if necessary.
•  Make sure power switch at heating & cooling system is on.
•  Make sure furnace door is closed securely.
•  If “Wait” is displayed, the compressor protection timer is on. Wait 5 minutes 
for the system to restart safely, without damaging the compressor.