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• The heater core is like a radiator device for your car cabin. But, if the heater core has accumulated a lot of dust, it won’t be able to function properly. So, if you are amongst those people who like to fix a car by themselves and maintain its health, then we are here to guide you through the process. In this article, we are going to tell you how to clean the heater core at home by using simple tools that would be available to you at home.

As mentioned earlier, the heater core is like a radiator for your car cabin. It heats the cabin of the car by using coolant from the engine. The antifreeze coolant absorbs the heat from the engine and passes it to the cabin through the cooling system. Before discussing how to clean a heater core, we will tell you some of the most common signs you will experience when the heater core has gone bad.

Signs That Your Heater Core Has Gone Bad And Needs To Be Cleaned

1. Fog in the car.
2. Your car cabin smells (mostly a sweet smell)
3. The cabin floor of the car is wet ( due to leakage of coolant)
4. Overheating of the vehicle

If you constantly observe any of these signs in your car, then the heater core is surely damaged or needs some cleaning. We will teach you how to flush out the heater core all by yourself.

How To Clean Heater Core?

Now that you are sure that your heater core needs to be flushed, let us look at how to clean it.

Materials Needed

1. Hose
2. Tube
3. 3/4 inch hose
4. Bucket
5. Pliers
6. Rags

Remember, every car manufacturer has a different size of hose that is used to feed the coolant to the heater core. So, look out for which size of hose you require and buy accordingly. If you can’t decide what size you require, look for some help online.

Step 1: Screw The Hose And Attach it To The Short Tubing

This, when attached to the outlet of the heater core, would reverse the flow and loosen any sediment present.

Step 2: Trace The Heater Core Hoses

The hoses run into the firewall. The heater core is located behind the dashboard of the passenger’s side, so that’s where you have to look for 2 thick hoses running through the firewall.

Step 3: Identify The Inlet And Outlet Hose Of The Heater Core

The easiest way to identify the inlet and outlet hose is by identifying the warmer hose. Turn the engine on and turn on the heater in the cabin. The hose that is warmer would be the inlet hose as it feeds the hot coolant to the heater core. The other is the outlet hose.

Warning: Perform step 3 a few hours before cleaning the heater core. This is because the engine should be cold during the process. If the engine is turned on or was on just a few minutes before opening up the cooling system, the coolant would also be hot which would be difficult to handle.

Step 4: Remove The Hoses

There would be a metal clamp holding the hoses. Pull them back using pliers and remove the hoses. You can also use some lubricants to loosen the clamps.

Pull the hoses back and forth as they might not come out easily. Also, you would see some discharge coming out from the outlet hose. While removing the inlet hose, you will see some coolant coming out. Make sure you do not touch it using bare hands. You could use gloves to avoid this.

Step 5: Attach The Garden Hose To The Outlet Valve

Now, as you have removed the outlet hose, attach the garden hose to the valve. This is to pump fresh water into the heater core and wash it out.

Step 6: Attach The Other Tubing To The Inlet

The other tube should be long and attached to the inlet of the heater core. Also, make sure you keep the other end in a bucket to collect all the sediment and coolant coming out from the heater core while flushing it.

Caution: Make sure you do not overflow the bucket. The coolant should be disposed of with proper measures as it is not an environmentally friendly fluid. So, keep an eye on it.

Step 7: Start The Water Flow

Now it’s time to clean the heater core. Turn on the water flow and maintain the pressure at about 10 psi. If you do not have any equipment to calculate the pressure, just keep the tap to half of its pressure.

Remember, too much pressure could damage the heater core. So, keep an eye on the pressure from the tap.

Step 8: Stop The Flow When The Water Coming Out Is Clean

Flushing the heater core should not take much time and when you see clear water coming out from the outlet of the long tube, you could turn it off.

Water Flow Is Restricted?

If the water flow has been restricted while flushing, this means that there is some clog or hard sediment stuck in the core. To unclog this, switch the hoses and again flush the system.

Step 9: Put Radiator Cleaner

After you flush the core and see clear water coming out of the outlet tube, remove the garden hose, keeping the outlet tube attached. Put some radiator cleaner into it.

Wait For 30 minutes. ( Always use a good quality radiator cleaner. You can get it online or at your local store)

Step 10: Flush The Radiator Cleaner

Turn the water inlet on and rinse out the cleaner until you see clear water coming out.

Step 11: Put Everything Back

Now, you have cleaned the heater core and you have to put everything back in its place. Remove the attached tubes and connect the inlet and outlet hose at their positions. Also, make sure you clamp them.

Go For A Test Drive

Congratulations on cleaning the heater core all by yourself. Now you could test if it is working properly by having a test drive. Turn the heater on and see if all the signs of a bad heater core are not present anymore.

Full Video Guide To Flush Heater Core

Check out the video below that would help you understand how to clean the heater core in cars more easily.

Q: Can A Clogged Heater Core Cause Overheating?

– A clogged heater core can cause engine overheating. Sometimes A low coolant level has a possibility of damaging the engine.

Q: Will A Radiator Flush Unclog The Heater Core?

– Yes, Radiator Flushing can unclog the heater core by removing the rust which passes through the heater core.

Q: Can You Drive With A Clogged Heater Core?

– Driving with a clogged heater core can lead to an increase in the temperature of the engine and damage engine components because it reduces coolant circulation.

Q: Will Vinegar Clean A Clogged Heater Core?

– Vinegar works well in removing rust particles because it is a mild acid generally 5% acetic acid that is safe to use on all metals

Q: Can You Fix A Heater Core Without Replacing It?

-Yes , heater core can be repaired more easily than by replacing it primarily because of its location It can be sealed off by applying radiator stop leaks products

Q: How Much Does It Cost To Get A Heater Core Flush?

-Flushing a clogged heater core can be done by any individual through the above steps and need not cost any money. However, if done by a mechanic it can cost around $100 to $200.

Q: How Much Is A Heater Core Replacement?

-Replacing a Defective heater is expensive and can cost around $550 to $964 including parts and labor, parts are however not expensive but because of its location labor costs are high.

Final Words

So, we have discussed all the steps on how to clean the heater core by ourselves. Make sure you follow all the precautions mentioned. Now, as you have learned how to clean the heater core, you should do this regularly to avoid buildup and clogging of the core.

If you like this article and have any queries related to flushing out the heater core, let us know in the comment section below.
Cheers!