How to Unlock the Screen on a Honeywell TH8320
The Honeywell TH8000 series is a line of programmable thermostats with digital displays. It is possible to lock the display screen to prevent unauthorized use. Once the screen is locked, you'll find that unlocking it doesn't take very much time and can be completed even if you don't know much about electronics.
Use the keypad to enter "0670" on the Honeywell thermostat. This is the system code and the screen will unlock when you enter it. If this doesn't solve the problem, proceed to the next step.
Pry the faceplate off of the thermostat to expose the batteries inside.
Remove the batteries and replace them. This will reset the display screen and clear anything that was previously locking the screen.
Fit the faceplate back over the unit.
Michael Wallace has been a freelance copywriter and journalist since 2003. He served in the U.S. Navy and attended the Academy of Art University in San Francisco. Specializing in writing technical articles, Wallace has contributed to city publications such as "San Diego City Beat."