If the heat in your vehicle has stopped working at optimum efficiency or you have experienced the catastrophic failure in the form of steam and hot water through your vent system. If either of these has happened, it is more than likely your heater core.
The heater core brings hot coolant into the cabin in a safe way to warm everything up in the interior. If your car doesn't get warm, it may be too clogged to allow fluid to flow through. It needs replaced or will fail soon from the coolant pressure.
This Part Fits the Following Vehicles