Carrier furnaces, like most modern furnaces, have flame sensors that alert the burner if more fuel is necessary for heating purposes. The flame sensor protects your furnace from burning too hot or not burning at all. After use, dust, dirt and sometimes even rust may cover the flame sensor. Cleaning the flame sensor will ensure your Carrier furnace remains in functioning condition.
Turn off the Carrier furnace and allow it to cool.
Open the burner maintenance hatch on the side of the Carrier furnace. Shine the flashlight into the burner assembly and locate the flame sensor. It is a long thin metal rod under the burners. Unscrew the flame sensor from the Carrier furnace with the screwdriver.
Wipe any surface dust from the flame sensor with a damp cloth. Scrub off any rust or ingrained dirt with the fine grit sandpaper.
Screw the flame sensor back into place. Close the Carrier furnace maintenance hatch.