What is Thermostat C-Wire?
The C-wire (“common” wire) is the thermostat wire that supplies continuous 24-volt power, letting smart thermostats run their screens and Wi-Fi without stealing power through the furnace control circuit. Many older homes were wired without one.
Why it matters in Arizona
Most smart-thermostat installs in older Greater Phoenix homes hinge on this one wire. Workarounds exist (adapter kits, battery-assist), but power-stealing setups can cause odd short-cycling on some systems — a properly run C-wire is the clean fix and a quick job for a tech.
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