Points to check before you call
Did you replace your furnace filter recently ? A dirty filter limits the air flow and overheats motors.
Did you replace the batteries in your thermostat? Corroded batteries will either shut your equipment off or can make it overshoot the temperature.
Are your outside vent ports free of debris or blockages? Snow, ice, leaves and bees are common possibilities.
Propane and oil customers: check your tank level.