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
How to install a Thermostat (C-wire adapter) - YouTube
hvac - Can I use this unused blue wire as my C wire for my new Nest thermostat? - Home Improvement Stack Exchange
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How To Identify A Thermostat Common Wire (C Wire) & What It Does For Smart Thermostats - YouTube
Amazon.com: Honeywell Home CWIREADPTR C-Wire Power Adapter : Everything Else
Xwartre UL Certified Thermostat C Wire 24V Transformer, White Adapter Compatible with Honeywell, Nest, Emerson, Ecobee, Wyze Thermostat and Most Doorbells (26FT Power Cable) - Amazon.com
Do I Need a C-Wire for My Thermostat? | Pickett Heating & Air
Power Up Your Comfort: The Smart Thermostat and C-Wire Guide - Gearbrain
Advice on how to wire a 4 wire RGWY wifi thermostat to an old hvac with no c wire? - Home Improvement Stack Exchange