As winter approaches, your furnace is the heart of a warm, cozy home. But when it starts acting up, it can feel like your heat is ghosting you—leaving you in the cold at the worst possible moment. Catching the scary signs of furnace trouble early can prevent costly breakdowns and keep your home safe and comfortable. Here’s what to watch for to know if your furnace needs a check-up or a full replacement, brought to you by the experts at Mr. Air Repair.