Turn off the power to the Carrier furnace by turning off the breaker in the circuit breaker panel.
Remove the Carrier furnace access panel. Locate the control board. On the control board there will be a terminal strip the thermostat wires tie into. The common wire is usually the black wire and it connects to the "C" terminal. Make this connection if it is not already made.
Replace the furnace access panel and go to the location of the thermostat.
Remove the thermostat from the wall by applying gentle pressure until it snaps off the wall plate.
Locate the black wire and strip it back with your wire stripper to expose 1/4 inch of bare copper wire.
Connect the black wire to the "C" terminal on the thermostat. Push the thermostat back onto the wall plate.
Turn the power back on to the furnace. Your thermostat should now be powered by the furnace entirely, unless the thermostat has batteries. Then it will be powered by the furnace when the batteries fail.
Things You Will Need
- Wire stripper
- If the thermostat uses batteries, replace them at least yearly. If for some reason the common wire doesn't transmit power to your thermostat, batteries are vital to keep the thermostat operating.