Honeywell T6 Pro Programmable Thermostat (TH6320WF / TH6220U) WONT-SWITCH Error Fix: Won't Switch Between Heat and Cool

Error code WONT-SWITCH on the Honeywell T6 Pro Programmable Thermostat (TH6320WF / TH6220U) means: Won't Switch Between Heat and Cool. The thermostat will not automatically switch between heating and cooling modes — verify the system is set to "Auto" mode (not just "Heat" or "Cool"), check that the auto changeover feature is enabled in installer settings, and ensure the heating and cooling setpoints have a minimum 2°F deadband between them; some non-programmable models do not support auto changeover

The most successful fix is "Test and Replace Thermostat Control Board for Auto Changeover Failure" (medium difficulty, ~50 minutes). Estimated DIY cost: $0-$20. HomeMD has 2 community-ranked fixes for this error.

This error is rated medium severity. It should be addressed soon, but your appliance may still function in a limited capacity.

Yes — the top-ranked community fix ("Test and Replace Thermostat Control Board for Auto Changeover Failure") is rated medium difficulty and takes about 50 minutes. Tools needed: T15 Torx screwdriver, Multimeter.

DIY cost: $0-$20. Professional repair typically costs $150-$220. Many homeowners save money by trying the top-ranked community fix first.

The Honeywell T6 Pro Programmable Thermostat (TH6320WF / TH6220U) has 8 other known error codes, including: APP-OFFLINE (Thermostat Shows Offline in App), AUX-HEAT ("Aux Heat" Displayed), BLANK-SCREEN (Blank/Dead Display — No Power), BLOWN-FUSE (HVAC Control Board Fuse Blown), COOL-ON-FLASH ("Cool On" Flashing on Display), and 3 more.

Error code WONT-SWITCH also appears on 7 other Honeywell models: RTH7600D 7-Day Programmable Thermostat with Backlit Display, RTH9585WF Wi-Fi Color Touchscreen 7-Day Programmable Thermostat, T10 Pro Smart Thermostat with RedLINK Room Sensor, T9 Smart Thermostat with Smart Room Sensor, TH4210U2002 PRO 4000 5-2 Day Programmable Thermostat, TH6220D1028 FocusPRO 6000 2H/2C Programmable Thermostat, and 1 more. The fix may vary by model, so check each model's specific page for tailored repair steps.