Mahle Behr Heater Core | 64111469197

The heater core is a small radiator inside your passenger compartment that uses hot engine coolant to warm air for the climate control system in your BMW. It consists of fin-covered metal coils connected to pipes or hoses that allow engine coolant to flow from the engine to the heater core and back. As hot coolant flows through the heater core, the blower motor pushes air through the heater core fins and is heated by the hot coolant in the core coils. The warm air is then directed out of the climate control vents to warm the passenger compartment.

Heater cores fail when they leak coolant, or the heater core coils become clogged. Heater cores leaking coolant replace the coolant with air, reducing the amount of coolant for the engine, which can cause the engine to overheat. Signs of a leaking heater core include:

• Coolant leaking into the passenger compartment.
• The climate control does not blow warm air when the engine is warmed up.
• Engine overheating from a lack of coolant.

Clogged heater cores restrict the flow of coolant through the heater core, reducing its ability to warm air for the passenger compartment. Signs of a clogged heater core are the climate control not blowing warm air or the air barely warming when the engine is warmed up.

Because most heater cores are located in the passenger compartment behind the dash, they can be very labor-intensive to replace. Removal of the dashboard may be required to access the heater core if there is no access panel under the dash or on the firewall to access the heater core. Some manufacturers have a heater box in the engine compartment for the heater box with ducts connecting the heater box and climate control ducts.

Engine coolant leaks and failed or leaking control valves that prevent coolant from flowing to the heater core can also prevent the heater core from warming the air in the passenger compartment, but they do not require the heater core to be replaced.

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