Check a smart thermostat before you buy one
Turn off power at the breaker, photograph the existing terminals, and compare them to the new thermostat’s compatibility list. Many homes have a C wire. Some do not, and a missing C wire is the usual reason an install stops. EasyTechdesk checks compatibility at the start of the visit. If the system needs a new transformer or heat-pump wiring, that work belongs to an HVAC technician, not a general tech visit.