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How to Flush A Heater Core? A Step by Step Guidance 

How to Flush A Heater Core

If you're searching for how to flush a heater core? All you need to do is locate the heater core, remove the hoses, apply some air pressure, use water flush, reconnect the hoses, and top off the coolant. 

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The heater core is a small component within your vehicle's cooling system. It works like a small radiator and helps maintain hot air temperature whenever you turn on your vehicle's heating system.

Over time of use, the heater core can get clogged with dirt and debris, requiring a quick flush. Flushing the heater core needs to happen at certain times depending on its condition. 

This article provides you with all details you need to know about when it's the perfect time for flushing your vehicle's heater core. It also provides step-by-step guidance on how to flush a heater core yourself to save on labor costs. 

What is the heater core, and what does it do? 

The heater core is a small component within your vehicle's cooling system. It is responsible for increasing the air temperature as you turn on the heating system in your vehicle. In short, the heater core acts like a small radiator by allowing the coolant to move around it and sending the excess heat to the cabin. 

When should I perform a heater core flush? 

Before we dive into the details about how to flush a heater core, It is important to understand when your vehicle is ready or due for a heater core flush.

Luckily, there are some symptoms you can keep an eye for informing you to perform heater core flush, including: 

  • The car heating system does not work properly 

When you notice that your vehicle is working properly and there is no clear issue in the cooling system, the heating system is not blowing hot air, there is a problem with that heater core, and it should be flushed soon.

Keep in mind that this problem might also be linked to other issues, and that's why you have to perform a thorough inspection before attempting to replace or flush the heater core. 

  • The vehicle has a sweet smell 

When you notice that your car smells sweet, this is an early sign indicating that your heater core is due for a flush. The problem here happens because of coolant spraying inside the vehicle's interior, and once you perform the flush, this smell should go away.

  • Fog well built up on the windows 

If you did not detect the sweet smell early in your vehicle, which indicates some coolant spraying into the interior, you might start dealing with fog building up on the windows.

This fog is another long-term outcome of coolant spraying to the vehicle's interior. Keep in mind that this fog is not something you can easily wipe off or clean, which gives you a very hard time and affects your vehicle's visibility.

The other thing to consider is inhaling this woman is dangerous, and it affects your health significantly. Therefore, when realizing any signs of coolant spraying inside your vehicle, you must immediately take care of the problem. 

  • Visible coolant leak 

In some severe scenarios, you might even start seeing coolant dripping under your vehicle's dashboard, which means that you have to perform a quick flush to your heater core. 

The engine might overheat 

As the coolant leaks repeatedly, the overall coolant level will drop in your car. Therefore, engine overheating can be the easiest and quickest outcome of a low coolant level. Thus, delaying heater core flush can cause severe outcomes if left for a very long time.

Engine overheating can also happen due to plenty of reasons, which means you have to confirm that the problem is coming from heater Corp by performing a thorough inspection. 

How to flush a heater core? 

Once confirming that your vehicle is due for a heater core flush, you can follow these steps:

  • Prepare all necessary equipment 

Before starting the process, you need to make sure that you have all the necessary equipment on hand so the process doesn't take you longer than it should. Here are some of the items you need to have ready:

  • Safety glasses
  • Rags
  • I want title products
  • 3/4-inch fitting adapter
  • Air compressor
  • Screwdriver
  • Garden hose
  • Gloves
  • Large bucket
  • Pliers
  • And clear tubbing 
  • Locate your vehicles heater core 

To get started, you need to know where the heater core is located. You can usually locate it by referring to your vehicle's owner’s manual or seeing any visual diagrams on the Internet for similar vehicles.

In general, the heater core is located within the car's firewall. By tracing back, the inlet and outlet hoses, he should be able to get to the heater core. 

  • Remove the heater core hoses 

Once you find the heater core, you need to disconnect both hoses and ensure that it is no longer connected to the firewall. To disconnect the hoses, you need to remove the clams using either a screwdriver or pliers. 

As you remove the hoses, make sure to put your bucket under them, so they collect any remaining coolant and prevent it from leaking to the ground. 

Coolant is not supposed to be disposed to their environment because it can be harmful to the living creatures; therefore come any collected: must be disposed of properly following the environmental regulations. 

  • Use the air compressor to apply pressure 

Hook the air compressor to the outlet hose of the heater core and secure it using duct tape, and applying pressure to remove any clogs within the heater core for about 10 minutes to get the perfect outcomes.

It's important to make sure that you don't apply too much pressure because it might damage the heater core. According to automotive experts, your heater core is OK with 20 to 40 PS I of pressure, but you can't put more than this.

  • Use a water hose to complete the flush 

After removing old gunk and clogs, you can go ahead now and connect the water hose to the heater core. Once it's connected, turn the water on and allow it to flush the heater core completely.

You can determine when it's the right time to stop water flush by looking at the coming water out of their heater core. If the water is clear, your job is done. It is sometimes recommended to repeat the process a couple of times to ensure that the heater core is completely flushed. 

  • Connect the heater core to the hoses 

After finalizing the heater core flush, you can reconnect the hoses while making sure that their heater core is drying out. It's also recommended that you have spare clams handy because many drivers had to deal with broken clams to reconnect the heater core. 

  • Top off the coolant level 

Once you're done, it is good to make sure that there wasn't any major coolant leak. To do so, you can measure the coolant level and top off any missing coolant to prevent engine overheating and any other complications. 

  • Give your vehicle a test drive 

Once everything is completed, you can test the heating system by turning it on and monitoring the air's temperature coming from the vents. If the temperature represents what it should, your done. On the other hand, if it's not heating up, you might need to consult a professional mechanic to inspect the car and see what exactly is going on and if you are done at the top right or not. 

How much does it cost to flush a heater core? 

In general, heater core flushing costs between $79 and $89. Of course, this range differs significantly depending on your vehicle's type and condition.

Determining the right location to get their heater core flushed plays a major role in your final bill. For example, if you decided to go to a dealership, repair costs will be much higher than going to a small repair shop.

Some people want to prefer to perform the heater core flush themselves since it's not a complicated job to save a lot on labor costs. Keep in mind that flushing your vehicle's heater core should not be done unless you're 100% comfortable that you can do the job shoot so you don't introduce additional complications to the car that might cost you thousands of dollars or more money than flushing your heater core at a repair shop. 

Can you unclog a heater core? 

Definitely! By performing a heater coil flush, you don't only remove and clean up the hoses but also unclog them. As we indicated in the step-by-step guidance earlier, you can connect it to the heater core and remove any gunk or debris by using an air compressor. 

Why is my trunk not blowing hot air? 

While there are plenty of reasons preventing your car from blowing hot air, a bad he or clogged heater core might be the culprit in many scenarios. Once you confirm that your heater core is clogged, it is recommended that you unclog it by performing a heater core flush so you can get the car heating systems to work properly again. 

What causes a bad heater core? 

The heater core is not designed to last forever, and there will be a point of time where you have to replace it or at least flush it. In most cases, that heater core had been still clogging from contaminated coolant. Clogs can build up over time and prevent the heater core from working completely.

Another common reason for a bad heater core is coolant leak somewhere else around the vehicle, which might affect the performance of the heater core. 

How long can you drive with a bad heater core? 

A bad heater core should not prevent you from driving your car. You will still keep going; however, if the heater core's problem is linked to some leak in the cooling system, it is never recommended to continue driving this car. You must take care of the problem immediately.

If the coolant leak became clear in some severe scenarios, the engine might overheat and get self-destructed within a short time.

Whatever reason preventing you from replacing the heater core should not be as important as dealing with major damages in the engine, which costs you thousands of dollars.  

You can flush your heater core by yourself or visit a small repair shop that can get the job done fast without wasting your time and effort. 


Performing regular maintenance helps increase your vehicles lifetime and prevents undesirable outcomes that can cost you thousands of dollars here at

Heater core flush is an essential maintenance practice, and it should be done whenever the new vehicle is due for one.

This article provided you with details about when to perform heater core flush. It also summarized the step-by-step guidance on flushing your vehicle's heater core yourself so you can save a lot on labor costs.

If you realize that your car's heater core problem is very complicated and there are additional major issues, it might be the right time to evaluate selling your car to Cash Cars Buyer.

Cash cars buyer is one of the fewest companies that accept your vehicle even if it has major problems in the heater core and major issues in the vehicle related to the engine or the transmission. 

The best thing about Cash Cars Buyers is that we pay the top dollars along with free towing service no matter where you're living around the United States. 

Our process is straightforward and involves three simple primary steps:

  • Describe your car's type and condition. This includes describing your car's make, model, and year. It is also important to let us know whether your car has a title or not. 
  • Receive or instant and free quote within 30 seconds
  • Get your vehicle removed and receive your cash payment immediately on the spot! 

To learn more about our process and our team, you can reach out to us by giving us a call at 866-924-4608 or visit our home page click on the free instant online offer.

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