Air conditioning and heating

Heater cores

Heater cores (heater matrices): the small radiator inside the heater box through which engine coolant warms the cabin air and clears the windscreen, made to the core size and the pipe stubs of the original, for European and Japanese passenger cars, identified by OE reference.

KRONTEK heater core: an aluminium heater matrix with two pipe stubs on one end

The heater core, or heater matrix, is a small radiator inside the heater box behind the dashboard. Hot engine coolant flows through it, the cabin blower pushes air through its fins, and the warmed air heats the cabin and clears the windscreen. It works whenever the engine is warm, with or without air conditioning, and on most cars it sits in the same box as the evaporator.

A heater core fails in two ways. It silts up: old coolant, corrosion products and sealant residue settle in its narrow tubes until little coolant passes and the heater blows lukewarm. Or it corrodes and leaks: coolant drips into the passenger footwell, mists the inside of the windscreen with a greasy film and fills the cabin with a sweet smell. Both are more likely on cars whose coolant has not been changed at the intervals the manufacturer gives.

KRONTEK heater cores are made to OEM-compliant quality and as aftermarket spare parts: the core size, the pipe stubs and the seals of the original, so the core fits the original heater box and hoses.

The range covers European and Japanese passenger cars. Each reference is identified by the OE number of the original part; send that number and the vehicle identification number (VIN) and we confirm the matching KRONTEK reference.

For availability and OE cross-references, contact us by email.

Frequently asked questions

What are the signs of a failed heater core?
Weak or no cabin heat with the engine at temperature, a sweet coolant smell inside the car, a greasy film on the inside of the windscreen and a damp passenger footwell. A blocked core gives only the first symptom; a leaking core gives all four.
Can a blocked heater core be flushed?
Sometimes, by back-flushing it with water through its stubs. A core that has silted up after years without a coolant change usually blocks again and is replaced; the coolant is renewed at the same time.

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