What are the symptoms of a clogged heater core?

Winter mornings can be challenging enough without the added discomfort of a car heater that’s failing to do its job. If your vehicle’s interior feels more like a fridge than a cosy retreat, a clogged heater core could be to blame. This small but crucial component of your car’s heating system plays a big role in keeping you warm and your windscreen clear.

Understanding the symptoms of a clogged heater core is essential for your comfort and for maintaining your vehicle’s overall performance. Let’s examine what to look for and how to address this common issue.

Is your car feeling frosty during winter?

Struggling to stay warm in your car on chilly mornings? A lack of heat could point to a clogged or malfunctioning heater core. This vital component works by circulating hot coolant from the engine through its tubes, with the blower motor pushing warm air across the core’s fins and into your cabin. Not only does it keep you toasty, but it’s also essential for defogging and defrosting your windscreen, ensuring clear visibility during those frosty winter drives. When your heater core isn’t working properly, comfort and safety can quickly take a back seat.

Symptoms of a clogged heater core

Without a properly functioning heater core, visibility can be compromised, making for an uncomfortable (and dangerous) ride during the cold months. Driving with a failed core could lead to bigger problems down the track, especially if the cause is leaking coolant. Sound familiar? Read more to find out how you can tell if something might be awry with your heating.

Natrad offers a nationwide warranty on new air conditioning parts fitted to your car. Need a new heater core? Get in touch today.

Heater core functionality

Before diving into the symptoms, it helps to understand how a heater core works. While it’s part of the air conditioning system, its primary role is to use hot engine coolant to deliver warm air into the cabin or defog the windscreen.

Think of the heater core as a miniature radiator. Hot coolant flows through its tubes, while air passes across its fins, absorbing heat along the way. This warmed air is then pushed into your car’s interior by the blower motor, keeping you comfortable and ensuring clear visibility on cold days.

In some vehicles, a valve controls when coolant flows into the heater core, ensuring it only activates when heating is needed. In other systems, coolant circulates through the core continuously, with a door or flap opening to direct warm air into the cabin. Regardless of the setup, the blower motor plays a key role, pushing air through the system and into your car’s interior whenever the air conditioning is turned on. This seamless process is what keeps you warm and comfortable.

If heating is desired, the air is directed through the heater core. If cooling is desired, the air is directed through the evaporator instead which is cooled by refrigerant.

Heater core failure symptoms

It will be pretty obvious if you are not receiving warm air inside the cabin or the defogging function isn’t working well. This is the first sign that something may have failed – and clogging isn’t the only culprit either. Have you noticed something isn’t quite right? Take a look at these signs and see if they apply to you.

Key signs to look out for:

• Weak or no airflow
• Cold air (not warm) coming through the vents when the heater is on
• Coolant leakage visible inside the cabin or a damp smell

What do these signs mean? A noticeable difference in airflow could indicate that the heater core fins have been clogged and are restricting airflow. A coolant smell or visible coolant leakage inside the car is a bit more sinister. This is likely due to a hole in the core somewhere and the coolant escaping into the cabin. This is typically where heater cores are situated. It may need to be replaced in order to get the system working again.

Important tip: coolant leakage inside the cabin can be dangerous for several reasons. Liquid near or on the pedals can make them slippery, and the liquid itself can encourage mould or rust which can then corrode the floor of your car.

If the cause of the problem is a leak, your car may be losing coolant slowly. If you notice a low coolant level but can’t locate the source of the leak, it could be escaping into the cabin of the car. Coolant loss will cause engine overheating which is not good for many parts inside the system!

What happens if the heater core goes out?

If the heater core goes out, you’ll likely experience a lack of heat inside the car’s interior. The heater core is responsible for providing warmth to the passenger compartment by circulating antifreeze through its core. A bad heater core can lead to several signs of a heater core issue, including a bad smell resembling sweet antifreeze and foggy windows due to condensation.

Another sign of a bad heater core is a coolant leak inside the car’s dashboard or passenger area. If you notice a leak in the heater core, it’s possible that there’s a clog in the system or a faulty thermostat, which can also cause the engine to overheat. If you don’t feel heat inside the vehicle’s cabin, take steps to consult a mechanic, such as Natrad for a heater core replacement as ignoring these common signs could lead to a serious problem with your automotive cooling system.

Get professional heater core replacements at Natrad 

If you’ve noticed any of the above symptoms, then it’s time to take action. Talk to a knowledgeable technician at your local Natrad store to properly diagnose the problem. The fault may be obvious or some deeper digging might be needed, but whatever repair is required, Natrad can help.

For new heater cores and any other part to fix your air conditioning system, Natrad is your one-stop shop. For fast service and a 12 month warranty, contact us today.