Heater Core - Possible Problems

Possible Problems

The heater core is made up of small piping that has numerous bends. Clogging of the piping may occur if the coolant system is not flushed or if the coolant is not changed regularly. If clogging occurs the heater core will not work properly. If coolant flow is restricted, heating capacity will be reduced or even lost altogether if the heater core becomes blocked. Control valves may also clog or get stuck.

Another possible problem is a leak in one of the connections to the heater core. This may first be noticeable by smell (ethylene glycol is widely used as coolant and has a sweet smell); it may also cause (somewhat greasy) fogging of the windshield above the windshield heater vent. Glycol may also leak directly into the car, causing wet upholstery or carpeting.

Electrolysis can cause excessive corrosion leading to the heater core rupturing. Coolant will spray directly into the passenger compartment followed with white colored smoke, a significant driving hazard.

Because the heater core is usually located under the dashboard inside of the vehicle and is enclosed in the ventilation system's ducting, servicing it often requires disassembling a large part of the dashboard, which can be time-consuming and therefore expensive.

One possible easy and inexpensive fix, depending on the severity of the leak, is to use a liquid Radiator Leak Sealant which can be obtained in any automotive parts supplier.