Ah, the lovely, sweet smell of antifreeze permeating your 740's interior...there's nothing like a bad Volvo heater core to ruin your day, especially if it's wintertime. Of course, since most of us don't use the heat in summer, we may not realize we have a bad Volvo heater core until that first really cold day. So what does a bad Volvo heater core mean? Basically, the Volvo heater core is a small radiator that hides under the dash in your car or SUV. When you call for cabin heat, a valve opens letting coolant from your engine circulate through the Volvo heater core. The fan blows air across the Volvo heater core, heating the air and sending it out into the passenger compartment. Remember how we mentioned that the Volvo heater core is like a small radiator? That means the Volvo heater core suffers from some of the same maladies that your full sized radiator can suffer from: namely, leaks and corrosion. But since the Volvo heater core is located under the dash rather than way out at the front of the car, you get coolant leaking onto your wool carpet rather than onto the street. If you're the adventurous sort, a Volvo heater core replacement might just be the ideal task for you to tackle yourself. For most of us, though, the number of components that have to be removed just to gain access to the Volvo heater core means that this job generally goes right to our favorite mechanic. And even he's been known to give us the stink eye for bringing in a Volvo heater core job!