What To Do If There’s No Heat After Coolant Flush?

So you might’ve done a radiator flush. But, now you’re observing that there’s no heat coming out of it. As if that’s not enough, you’re even facing cold air from the heaters of your vehicle.

Why is there low heat after coolant flush?

At times, your radiator still has air bubbles left inside of it. As a result, it doesn’t allow heat to come out and lets out cold air. Moreover, sometimes you have an object stuck inside after coolant flush. This can cause this issue.

no heat after coolant flush

So, what should you do if there’s no heat after coolant flush?

Don’t fret, we’ve got your back. In fact, we’ve compiled some simple methods that you can follow to fix this issue. Also, we’ve even discussed why heat doesn’t come out after a coolant flush.

Furthermore, we’ve prepared a FAQ session at the end that’ll clear off most of your confusion about this problem.

Got a little time to check our article? Let’s begin.

Why Doesn’t Heat Come Out After A Coolant Flush?

Well, if the heat doesn’t come out, it’s not normal. It probably means you haven’t done coolant flush correctly. At times, any foreign object or the air bubbles can be the culprit to this problem.

Turns out, even foam in the radiator can cause warm air to not come out. So, let’s look at some of the factors that contribute to heat not coming out:

●  Presence Of Air Bubbles

Around 30% of the time, it’s the air bubble inside the radiator that causes heat to not come out. Also, air bubbles can also cause the water to be foamy.

But, how to tell if air in cooling system?

Well, if you have leakage in the radiator cap, air can enter easily in the cooling system.

●  Clogged Up Heater Core

Many times, when you flush the cooling system, gunk enters into the heater core and clogs it up. As a result, the heater core fails to provide warm air.

● Dirt and Rust Inside The Heater Core

Around 50% of the time, dirt and rust are the main reasons why a heater core doesn’t provide warm air. Dirt and rust clog up the core and don’t let warm air come out.

Hence, you’re stuck with cold air. On the other hand, coolant flush doesn’t always clear the dirt and debris inside the heater core.

● Weeping Water Pump or Bad Thermostat

Yes, you heard me right. A bad thermostat or water pump can also cause the heater to stop working.

At times, when the water pump doesn’t work completely, it doesn’t send water through the engine. As a result, the heat doesn’t stay warm and cold air takes place.

The Fixing Guide

So, by now you already know about what leads to this problem in the first place. But you shouldn’t worry if this problem exists in your car. This is because we’ve compiled some simple methods for you to solve this problem.

Moreover, we’ve even shown what tools you’ll need for the job. If you can follow the methods and their steps correctly, you’ll eventually fix this problem. So, without further ado, let’s look at what you should be doing to tackle this situation:


Yes, you’ll need a set of tools for the job. However, the tools are available and affordable. So, you can purchase them easily from the local shops at a convenient price. Let’s take a look:

After you’re done managing the tools and making all the preparations, let’s begin with the methods:

Method 1: Burping Air Out Of The Radiator

Yes, you heard me right. The air inside the radiator can cause the heater core to not provide warm water. So, it’s essential that we take care of it. Moreover, this method is simple and you can burp radiator without funnel.

That being said, let’s look at the step-step process:

Step 1: Elevate The Car

It’s best if you drive the car into the driveway so that the rear is elevated. After this, turn off the engine. Use a wrench for the bolts in the place and take the red cap of.

Step 2: Make Sure The Car is cold

Before beginning the process, make sure that the car hasn’t been started recently. It’s essential that the car is cold. So, make preparations the day before.

Step 3: Use a Bucket For The Coolant.

You’ll have to pour in fresh coolant into the reservoir cap. But wait, let me tell you something.

As you’re pouring in fresh coolant into the reservoir, you don’t want the coolant to go waste, do you? So, in this situation, use a bucket so that you can store the fresh coolant after it pours out.

Step 4: Remove The Reservoir Cap & Pour Coolant.

This step sounds pretty simple, doesn’t it? However, make sure there’s always enough coolant in the reservoir. So, never let it dry out.

Step 5: Turn The Engine.

After this, start the engine and make sure that the heat is turned to the max option. Keep it for a few minutes.

On the other hand, always make sure that the reservoir has enough coolant. Remember to not let it dry out any time during this process.

Step 6: Keep The OEM Tube is Higher Than The Bleeding Valve.

Remember to keep the OEM tube at a higher level than the bleeding valve. The bleeding valve will drain to the bucket.

Step 7: Open The Valve & Rev Your Engine.

After this, open up the valve so that the coolant and the air escape into the bucket. Following this, rev the engine of the car. By doing this, most of the air comes out of the car and the coolant gets stored in the bucket.

Step 8: Close Valve

Close the valve and store the coolant to the reservoir. This is why you should store the coolant into the bucket so that you can use it later for the same purpose.

Step 9: Repeat The Process

If the reservoir is dry then you’ll have to repeat the process. You can repeat it 9-10 times or even more until the heater gives off warm air. However, don’t overdo this.

Step 10: Add Coolant & Secure The Cap

Lastly, if you feel all the air is out of the system, put the cap back into its position. Also, add the coolant into the reservoir at a max level.

After this, run the car and test to see whether warm air is stable now or not.

Method 2: Car Heater Repair

If there’s no heat after the coolant flush, there could be a problem in the heater. So, what should you do? Well, it’s really simple. You can easily repair the heater by following some simple steps. So, let’s begin:

Step 1: Add Coolant/Antifreeze

A heater doesn’t work well if the engine doesn’t have enough coolant or antifreeze. So, make sure that your engine has enough coolant and antifreeze, to begin with.

Apart from this, observe if there’s any leak in the reservoir. Due to leaks, the engine fails to receive a sufficient amount of coolant. As a result, the heater fails to provide warm air.

Step 2: Replace the Thermostat

A faulty thermostat can cause the heater to not work properly. Also, a faulty thermostat causes the engine to not heat up as well.

If you have a faulty thermostat in your engine, get it replaced. Thermostat replacements don’t cost much and you can do their replacement easily. That should help with the no heat after coolant flush.

Step 3: Replace the Actuator

An actuator can cause the blend door to malfunction. As a result, the heater fails to provide heat. So, check if the actuator is causing a problem. If it is causing a problem, get it replaced.

Step 4: Fix the Heater Control Valve

Do you hear a hissing sound when you turn the car on? If that’s the case then you might have problems with the valve of the heater. This valve can cause the heater system to not work.

Mostly, a vacuum leak can cause this too. So, you need to get them replaced.

Method 3: Fixing Clogging In The Coolant or Heater Core

After a coolant flush, some of the debris or foreign particles can still get stuck inside the heater core. As a result, this does contribute to the heater core getting clogged up. So, you need to fix the clogging issue by following these steps:

Step 1: Take Both Hoses off

Make sure that both the hoses are off. After this, connect the water hose to the other hose. Following this, run the water into the system at a slightly lower pressure.

Step 2: Flush The Cleaner In The System

Firstly, use the cleaner from any local store and flush it into the system a few times. Also, you can even clean heater core with vinegar.

Step 3: Repeat

Repeat the process again and again. After this, you’ll see that the water coming out is clean and free.

Step 4: Reattach The Hoses & Cap Off The Radiator

After you observe clean water coming out, reattach the hoses and turn the cap off. Make sure the cap is tight.

Step 5: Turn On The Engine

Start the engine and rev it. After this, you’ll see warm air entering. And yes, you’ve got dirt and air bubbles out of the system.

Frequently Asked Questions

Does coolant flush absorb heat?

Yes, a coolant flush absorbs the heat from the engine so that it doesn’t heat up much in the summer.

Do you need a coolant flush?

Yes, it’s important that you get a radiator flush now and then.

You may also like: How to Flush a Radiator?

Wrapping Up

That’s all we have for you. By now, you’ll know why there’s no heat after coolant flush. Moreover, you even know what you can do to fix that issue.

In the end, we’d like to say that these are simple methods and you can do this by yourself. But, if you’re not comfortable, get a professional to do it.

So, why don’t you try it for yourself? Good Luck.

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