Our furnace seems to run a lot-it is constantly running but the air is on the cool side-the fan is on auto

Is it electric ,gas, or oil? with these questions answered,if it is gas is everything working,, gas burners,fan,, if electric ,do you have a multo-meter to check to see if the elements are working/pulling power,, also could you give us the tempature of the air coming out your supply vents?