(610)644-0537Few things are more frustrating on a chilly day than turning on your furnace—only to feel cold air blowing through your vents. While it’s an uncomfortable surprise, the good news is that many causes of cold-air issues are simple, fixable, and sometimes even temporary. Before you panic, here’s what you should check when your furnace is blowing lukewarm or cool air, suggestions for things to check, and how to know when it’s time to call in a professional.