How do I set up the system mode (Heat, Cool, or Auto)?
Press the Menu button, then press the Mode (+) button to cycle through available system modes. Cycle through the modes until the required mode is displayed, then press Done to save your selection. Available modes vary by model and system settings.
From the official Honeywell T3 Pro Programmable Thermostat manual, page 5
Have a follow-up question?
Answers from the official manual.
Common questions