The Ford heater core is the heart of your car's heating system, utilizing engine heat to warm up the passenger compartment on cold mornings. So how does the Ford heater core accomplish this? In essence, the Ford heater core is a little radiator, comprised of tubes, fins, and an inlet and outlet to which heater hoses connect. When you use your climate control system to dial up some heat, a valve opens allowing hot engine coolant to flow into the Ford heater core. The fan blows air over the Ford heater core, which warms it, after which it flows into the passenger compartment. We mentioned that the Ford heater core is similar to a small radiator: That's true in several ways, including the problems that a Ford heater core is susceptible to. Your Ford heater core can clog due to debris in the cooling system, or corrode due to old coolant being used in the system. Either way, you end up with a significant drop in heat output from the Ford heater core, and possible leaks in your interior. The later situation is particularly troublesome since a pinhole leak in the Ford heater core can go undetected for months, resulting in rust in your floorpans. While a Ford heater core is no picnic to replace, it's far less involved than welding in new sheetmetal underneath your seats. So, keep an eye out for the symptoms of a failing Ford heater core. A reduction in heat output can indicate a clog, while a mysterious loss of engine coolant combined with humidity in the passenger compartment can indicate a leak in the Ford heater core. If either situation crops up, get your Ford heater core checked out by a professional.