4 Ways Your Vehicle's Heater Core Can Fail

19th Feb 2020

man sitting in car at dashboard

Vehicle Heater Core Failure

Has your vehicle's cabin heat stopped working? It's frustrating when you turn on the cabin heat during the winter, only to discover that the air isn't warm. Normally, this is the result of a failed heater core. If the heater core fails, it won't produce warm air -- even if you adjust the temperature controls in the cabin. Below are four common reasons why heater cores fail.

#1) Cracking

Heater cores can fail by cracking. If a crack forms, coolant will leak out of the heater core after your vehicle's engine has warmed up. A warm engine causes the coolant to pressurize, and if there's a crack in the heater core, the pressurized coolant will escape through it. As the coolant level in your vehicle's heater core drops, it may not have a sufficient amount to produce warm air.

#2) Clogging

Another way heater cores can fail is by clogging. Although there are dozens of types, all heater cores work in the same way: They feature hollow pipes that run vertically from a horizontal top container and a horizontal bottom container.  The hollow pipes in a heater core, however, are very narrow. As a result, dirt and debris often gets stuck inside them.

With a clogged heater core, coolant won't be able to flow through it. Rather, it will become trapped at the area where the clog is located. And like with cracking, if coolant can't flow through your vehicle's heater core, the heater core won't produce warm air.

#3) Infrequent Coolant Changes

When was the last time that you changed your vehicle's coolant? Infrequent coolant changes are one of the most common reasons why heater cores fail. Most automakers recommend changing the coolant every 30,000 to 50,000 miles. If you've driven your vehicle a longer length without a coolant change, it will place your vehicle's heater core at risk for failure.

Coolant contains more than just water and antifreeze; it contains compounds that protect against corrosion. Over time, coolant will lose these compounds, at which point corrosion may build up inside the radiator, hoses and heater core.

#4) Loose Connectors

A loose connector can cause your vehicle's heater core to fail. Heater cores feature connectors where they join with coolant hoses. There are several types of connectors, including gear worm, spring clamp, wire clamp and ear clamp. Regardless, though, it's not uncommon for heater core connectors to loosen over time.