![Trying to replace this old 2 wire thermostat for a newer digital one. Problem is older unit does not have leads labeled or which cable is which. Any help on how to Trying to replace this old 2 wire thermostat for a newer digital one. Problem is older unit does not have leads labeled or which cable is which. Any help on how to](https://i.redd.it/j9mnonzn7nu91.jpg)
Trying to replace this old 2 wire thermostat for a newer digital one. Problem is older unit does not have leads labeled or which cable is which. Any help on how to
![wiring - 2 wire thermostat wire want to be able to select fan only - Home Improvement Stack Exchange wiring - 2 wire thermostat wire want to be able to select fan only - Home Improvement Stack Exchange](https://i.stack.imgur.com/eH39I.jpg)
wiring - 2 wire thermostat wire want to be able to select fan only - Home Improvement Stack Exchange
![Two 2 wire Honeywell digital thermostat to replace mercury switch. Convert from mercury switch - YouTube Two 2 wire Honeywell digital thermostat to replace mercury switch. Convert from mercury switch - YouTube](https://i.ytimg.com/vi/YqTUSs56E7A/maxresdefault.jpg)
Two 2 wire Honeywell digital thermostat to replace mercury switch. Convert from mercury switch - YouTube
![2-Pack Honeywell THX9421R5021WW 2 Wire IAQ High Definition Touch Screen Thermostat with Red LINK Technology -White + LCD Cleaner - Walmart.com 2-Pack Honeywell THX9421R5021WW 2 Wire IAQ High Definition Touch Screen Thermostat with Red LINK Technology -White + LCD Cleaner - Walmart.com](https://i5.walmartimages.com/seo/2-Pack-Honeywell-THX9421R5021WW-2-Wire-IAQ-High-Definition-Touch-Screen-Thermostat-with-Red-LINK-Technology-White-LCD-Cleaner_3d5920de-20e6-48c0-be42-bfce8ab46d12.61e990e10737b1f8fde053aecc2dfe9d.jpeg?odnHeight=768&odnWidth=768&odnBg=FFFFFF)
2-Pack Honeywell THX9421R5021WW 2 Wire IAQ High Definition Touch Screen Thermostat with Red LINK Technology -White + LCD Cleaner - Walmart.com
![Old Honeywell 2 wire AC thermostat (with 1 extra wire behind) - can I modernize this with Ecobee? : r/ecobee Old Honeywell 2 wire AC thermostat (with 1 extra wire behind) - can I modernize this with Ecobee? : r/ecobee](https://i.redd.it/old-honeywell-2-wire-ac-thermostat-with-1-extra-wire-behind-v0-zgb7bnf4hv2b1.jpg?width=3024&format=pjpg&auto=webp&s=260717dc10e09aa7edef141b700365ef3292e75f)
Old Honeywell 2 wire AC thermostat (with 1 extra wire behind) - can I modernize this with Ecobee? : r/ecobee
![Hotop C Wire Adapter 24 Volt Transformer Compatible with Nest Honeywell Ecobee Emerson Sensi Smart WiFi (White) - Amazon.com Hotop C Wire Adapter 24 Volt Transformer Compatible with Nest Honeywell Ecobee Emerson Sensi Smart WiFi (White) - Amazon.com](https://m.media-amazon.com/images/I/71nKqB-nArL._AC_UF1000,1000_QL80_.jpg)
Hotop C Wire Adapter 24 Volt Transformer Compatible with Nest Honeywell Ecobee Emerson Sensi Smart WiFi (White) - Amazon.com
![2 to 8 Wire All Thermostats Wiring Diagrams (Honeywell, Nest) | Thermostat wiring, Thermostat, Electrical diagram 2 to 8 Wire All Thermostats Wiring Diagrams (Honeywell, Nest) | Thermostat wiring, Thermostat, Electrical diagram](https://i.pinimg.com/originals/45/2d/cd/452dcd199d840f3929b6b52f03c0481b.png)
2 to 8 Wire All Thermostats Wiring Diagrams (Honeywell, Nest) | Thermostat wiring, Thermostat, Electrical diagram
![Honeywell Home Wi-Fi Smart Color 7-Day Programmable Smart Thermostat with Color-Changing Touchscreen Display (2-Pack) RTH9585WF10042PK - The Home Depot Honeywell Home Wi-Fi Smart Color 7-Day Programmable Smart Thermostat with Color-Changing Touchscreen Display (2-Pack) RTH9585WF10042PK - The Home Depot](https://images.thdstatic.com/productImages/5daa2692-26df-48ca-b454-6d6be8b4dbf2/svn/metallic-honeywell-home-programmable-thermostats-rth9585wf10042pk-64_600.jpg)
Honeywell Home Wi-Fi Smart Color 7-Day Programmable Smart Thermostat with Color-Changing Touchscreen Display (2-Pack) RTH9585WF10042PK - The Home Depot
![Wiring a Honeywell Room Thermostat - Honeywell or Resideo Thermostat Wiring Connection Tables & Hook-up Procedures Wiring a Honeywell Room Thermostat - Honeywell or Resideo Thermostat Wiring Connection Tables & Hook-up Procedures](https://inspectapedia.com/heat/Thermostat_Install_129_DJFs.jpg)
Wiring a Honeywell Room Thermostat - Honeywell or Resideo Thermostat Wiring Connection Tables & Hook-up Procedures
![Old Honeywell 2 wire AC thermostat (with 1 extra wire behind) - can I modernize this with Ecobee? : r/ecobee Old Honeywell 2 wire AC thermostat (with 1 extra wire behind) - can I modernize this with Ecobee? : r/ecobee](https://i.redd.it/old-honeywell-2-wire-ac-thermostat-with-1-extra-wire-behind-v0-rure8of4hv2b1.jpg?width=3024&format=pjpg&auto=webp&s=9df111248d2d94a5587646e86b479512b160e3cd)
Old Honeywell 2 wire AC thermostat (with 1 extra wire behind) - can I modernize this with Ecobee? : r/ecobee
![heating - Wifi thermostat to replace old mechanical 2-wire 110V Honeywell? - Home Improvement Stack Exchange heating - Wifi thermostat to replace old mechanical 2-wire 110V Honeywell? - Home Improvement Stack Exchange](https://i.stack.imgur.com/YnlT0.jpg)