If you've ever had your furnace fail in the dead of winter—or your air conditioner kick out on you in the sweltering heat of summer—you know that indoor comfort does not come cheap. The cost to repair or replace an old unit is steep, to be sure, so take the steps now to make sure yours has a long happy life. First step? Make sure you change the air filter as often as necessary. FOR THE REST OF THE STORY CLICK HERE