![Does anyone know I can install a smart thermostat without additional wiring? How can I tell if the blue wire is the C wire? It's an air handler for a/c only. : Does anyone know I can install a smart thermostat without additional wiring? How can I tell if the blue wire is the C wire? It's an air handler for a/c only. :](https://preview.redd.it/x4o2gcbyfym91.jpg?width=640&crop=smart&auto=webp&s=31429b7c9e94f8a7ccdf5cba3a8bf9bc94e7629e)
Does anyone know I can install a smart thermostat without additional wiring? How can I tell if the blue wire is the C wire? It's an air handler for a/c only. :
![Old thermostat works, but I can't get the Honeywell T9 to work. T9 require C Wire that was not in the wall. I added C wire & RC wire via plug-in 120v Old thermostat works, but I can't get the Honeywell T9 to work. T9 require C Wire that was not in the wall. I added C wire & RC wire via plug-in 120v](https://i.redd.it/qgn9tccrp6a91.jpg)
Old thermostat works, but I can't get the Honeywell T9 to work. T9 require C Wire that was not in the wall. I added C wire & RC wire via plug-in 120v
![Honeywell home ventilation system with no c wire for thermostat. How can I substitute the g for the c without blowing a fuse? - Home Improvement Stack Exchange Honeywell home ventilation system with no c wire for thermostat. How can I substitute the g for the c without blowing a fuse? - Home Improvement Stack Exchange](https://i.stack.imgur.com/nqLQO.jpg)
Honeywell home ventilation system with no c wire for thermostat. How can I substitute the g for the c without blowing a fuse? - Home Improvement Stack Exchange
![Thermostats 24 Volt Transformer C Wire Power Adapter for Nest, Ecobee, Honeywell WiFi Thermostats, Power Supply for Nest Hello, Ring Smart Doorbells Chime - Amazon.com Thermostats 24 Volt Transformer C Wire Power Adapter for Nest, Ecobee, Honeywell WiFi Thermostats, Power Supply for Nest Hello, Ring Smart Doorbells Chime - Amazon.com](https://m.media-amazon.com/images/I/71qO0x7bNcL.jpg)