Bad heater core symptoms

Bad heater core symptoms

A heater core is a small radiator heat exchanger that sits under your dash and heats cabin air. The engine circulates hot coolant through the heater core and the blower motor sends cabin air through it to be heated.

A bad heater core is usually clogged with rust debris and won’t transfer heat from the coolant.

There are five heater core symptoms

1) Wet carpet — Coolant leak in the cabin or under the vehicle. If the core is leaking, coolant will leak into the heater box, the plastic unit with blend and mode doors that adjusts heat and directs the heated air to the dash, floor and windshield. If coolant fills the heater box, it can leak out, soaking your carpet with coolant.

2) Puddle under your vehicle — If coolant leaks into the heater box, it can sometimes drain out the condensate tube and form a puddle under your car.

3) Greasy film on your windshield — If the core is leaking and you switch the HVAC to the defrost mode, it can blow coolant mist onto the windshield, forming a greasy film on your windshield.

4) No heat — Loss of coolant due to a leak will cause a no-heat condition and the coolant level in your reservoir will be low. In addition, a plugged core won’t allow hot coolant to circulate and will cause a no-heat condition.

5) Sweet smell in the cabin — Coolant has a sweet smell and that smell will get stronger if you boost the blower motor speed.

What goes bad on a core?

Heater core leaks

A core can leak three ways:

Internal corrosion — Not changing your coolant on time can wear out the anti-corrosion inhibitors in your coolant. Due to the different metals used in the cooling system electrolysis begins and attacks the thin tubes in the core, eating small holes in them, resulting in leaks.

Physical damage due to flexing — The tubes that connect to the heater hoses are soldered to the heater core. Applying too much force to the tubes while removing/installing the heater hoses can break the solder bond, causing a leak.

Excessive coolant flow — Too much coolant flow can wear out the thin tubes in the core, causing them to leak. Excessive flow is caused by the removal of a factory installed flow restrictor when servicing the heater hoses. Factory restrictors must NEVER be removed from the lines.

To learn more about heater core replacement costs, see this post

©, Rick Muscoplat