can a heater go out in a car

[SarahRose]

Yes, a car heater can absolutely stop working, and it's usually a symptom of an underlying issue with the engine's cooling system. Since the heater uses hot engine coolant to warm the cabin, a failure often points to problems like low coolant level, a faulty thermostat, a clogged heater core, or a malfunctioning blend door actuator. Diagnosing the specific cause is key to getting warm air flowing again.

The most common culprit is a low coolant level. Your car's heater works by diverting hot engine coolant through a small radiator called the heater core. A small fan then blows air over this hot core to heat the cabin. If the coolant level is low, there isn't enough hot liquid to circulate through the heater core, resulting in cold or lukewarm air. Check the coolant reservoir when the engine is cool; if it's low, you may have a leak.

A stuck-open thermostat is another frequent issue. The thermostat regulates engine temperature by opening to allow coolant to flow to the main radiator when the engine is warm. If it's stuck open, the engine never reaches its optimal operating temperature, meaning the coolant is never hot enough to provide heat.

More involved problems include a clogged heater core, which blocks coolant flow, or a failure of the blend door actuator, which is the electric motor that controls whether air is directed over the hot or cold side of the system. You might hear a clicking sound from the dashboard if the actuator is failing.

Here’s a quick reference for common symptoms and their likely causes:

Symptom	Most Likely Cause	Other Possible Causes
No heat, engine temperature gauge reads low	Stuck-open Thermostat	Low coolant level
No heat, engine temperature is normal	Low Coolant Level	Clogged Heater Core, Water Pump Failure
Heat only works at high RPMs	Low Coolant Level	Failing Water Pump
Clicking noise from dashboard when adjusting temperature	Faulty Blend Door Actuator	-
Sweet smell and/or foggy windshield	Heater Core Leak	-

If your heater goes out, it's best to have it inspected. While you might manage without heat, the root cause could lead to engine overheating and significant damage.

[Allison]

Sure can. It's almost always tied to the engine's cooling system. If your coolant is low, you won't get any heat. Same thing if the thermostat is stuck open—the engine won't get hot enough. It's more than just a comfort issue; it can be a warning sign of a bigger problem. Get it checked out before a small leak turns into a costly engine repair.

[OSadie]

Mine went out last winter during a road trip. I had the blower on full blast but only cold air was coming out. Turns out, a small hose had sprung a leak and all the coolant had slowly dripped out. The mechanic said it's a really common problem, especially in older cars. It was an easy fix, but I learned my lesson about paying attention to those little warning signs.