Hot coolant from the engine is circulated through the heater core to provide heat in the passenger compartment of a vehicle. The heater core is located behind the dashboard. The driver operates a lever that controls how much hot coolant passes through the heater core.
To replace the heater core, the cooling system is drained and major disassembly of the dashboard and interior of the vehicle is necessary. If the vehicle has air conditioning, it is likely that the AC system will have to be evacuated and recharged during this repair.