![hvac - How can I modify a 4 wire thermostat to a new thermostat requiring c wire? - Home Improvement Stack Exchange hvac - How can I modify a 4 wire thermostat to a new thermostat requiring c wire? - Home Improvement Stack Exchange](https://i.stack.imgur.com/a3Dsi.png)
hvac - How can I modify a 4 wire thermostat to a new thermostat requiring c wire? - Home Improvement Stack Exchange
![Blue "C" wire is connected to "Y" on old thermostat. New thermostat has separate "C" hookup. Where does the blue wire go - "Y" or "C"? : r/Nest Blue "C" wire is connected to "Y" on old thermostat. New thermostat has separate "C" hookup. Where does the blue wire go - "Y" or "C"? : r/Nest](https://i.imgur.com/qa9UXyW.jpg)
Blue "C" wire is connected to "Y" on old thermostat. New thermostat has separate "C" hookup. Where does the blue wire go - "Y" or "C"? : r/Nest
![THE CIMPLE CO - Thermostat Wire 18/4 -Brown- 18-Gauge Solid Copper 4-Conductor CL2/CMR - 50ft - Walmart.com THE CIMPLE CO - Thermostat Wire 18/4 -Brown- 18-Gauge Solid Copper 4-Conductor CL2/CMR - 50ft - Walmart.com](https://i5.walmartimages.com/asr/916c250e-731a-4bc5-8367-c7d856870915_1.d95322bfdf5680b94851bec6ec4a851c.jpeg)
THE CIMPLE CO - Thermostat Wire 18/4 -Brown- 18-Gauge Solid Copper 4-Conductor CL2/CMR - 50ft - Walmart.com
![Amazon.com: C Wire Accessory Common Wire Kit for Most 24 VAC Thermostats (4 to 5 Wires), White (1 Pack) : Tools & Home Improvement Amazon.com: C Wire Accessory Common Wire Kit for Most 24 VAC Thermostats (4 to 5 Wires), White (1 Pack) : Tools & Home Improvement](https://m.media-amazon.com/images/I/71XSABB637L.jpg)
Amazon.com: C Wire Accessory Common Wire Kit for Most 24 VAC Thermostats (4 to 5 Wires), White (1 Pack) : Tools & Home Improvement
![Venstar ACC0410 Add-A-Wire Accessory for 24 VAC Thermostats (4 to 5 Wires), White: Amazon.com: Tools & Home Improvement Venstar ACC0410 Add-A-Wire Accessory for 24 VAC Thermostats (4 to 5 Wires), White: Amazon.com: Tools & Home Improvement](https://m.media-amazon.com/images/I/61jSbhoa03L.jpg)
Venstar ACC0410 Add-A-Wire Accessory for 24 VAC Thermostats (4 to 5 Wires), White: Amazon.com: Tools & Home Improvement
![Advice on how to wire a 4 wire RGWY wifi thermostat to an old hvac with no c wire? - Home Improvement Stack Exchange Advice on how to wire a 4 wire RGWY wifi thermostat to an old hvac with no c wire? - Home Improvement Stack Exchange](https://i.stack.imgur.com/j5dG1.jpg)
Advice on how to wire a 4 wire RGWY wifi thermostat to an old hvac with no c wire? - Home Improvement Stack Exchange
![hvac - How can I modify a 4 wire thermostat to a new thermostat requiring c wire? - Home Improvement Stack Exchange hvac - How can I modify a 4 wire thermostat to a new thermostat requiring c wire? - Home Improvement Stack Exchange](https://i.stack.imgur.com/iKWAum.jpg)