Air conditioning you can live without, but heat? Well, it depends upon where you live, but in most places you're going to want a working Pontiac heater core in your Firebird or Grand Prix at least a few months of the year. Why? Well, let us put it simply: No Pontiac heater core means no heat. Or, more precisely, a non-functioning Pontiac heater core means no heat. So how does the Pontiac heater core generate heat for your passenger compartment, and how does it fail? Contrary to popular belief, your car's interior isn't heated by electricity or gasoline, at least not directly. Instead, a small radiator called the Pontiac heater core sits up in the dashboard of your vehicle with engine coolant flowing through it. Engine coolant is heated by the gasoline burning in your engine, which is why we say the Pontiac heater core doesn't work directly off of gasoline, even though it does receive its heat from burning fuel. When you need heat, the fan blows air over the Pontiac heater core, warming it up. When you don't need heat, the Pontiac heater core is either bypassed by the coolant or by the interior air, or both. Simple, right? Yes, as long as the Pontiac heater core isn't leaking or plugged up. Either of these situations will cause a loss of heat output from the Pontiac heater core, and possibly a soaking wet interior. Needless to say, the latter is much more serious, and any trace of green or orange engine coolant on the inside of your vehicle needs to be investigated immediately. If a bad Pontiac heater core is discovered, replace it with one of our exact-fit OE replacement Pontiac heater core units. You'll be toasty warm and your interior won't reek of mildew anymore, plus your new Pontiac heater core won't cost you an arm and a leg.