The causes and symptoms of car overheats when ac is on. (With Solutions)

Nothing hurts more than driving a car that suddenly gets hot while the AC is on, on a hot summer afternoon. It’s worse if you were going on a road trip with a few of your friends.

At this point, a lot of wishes would come to you at a time. But most importantly, you’d wish that the car AC didn’t radiate so much heat than cool at that moment.

Because of bummer! It’s ruining the entire cool summer vibe you were having with your friends in the car before it started. Now, you have to wind down the car window and depend on natural air.

That’s sad! But it happens occasionally; the car overheats when AC is on, And, yeah, it does happen to the best of us.  So, it’s nothing to be ashamed of. Rather than be embarrassed, channel your effort to solving the AC problem.

We’ve addressed some of the causes of this problem and what to do when your AC starts malfunctioning. Keep reading to find out.

What causes a car to overheat when ac is on?

There are few culprits you can hold responsible for your car overheating when the AC is on. We’ll quickly examine some of these causes. You’ll also find out if it’s some of these causes are manmade or an innocent malfunction. Let’s dive in.

Cooling Fan:

Your AC would start to overheat when the cooling fan breakdown. Imagine getting stuck in traffic for hours. Then, you notice that the AC starts to overheat. This malfunction can be a result of your cooking fan. The reason? The cooling fan is responsible for radiating cool to the motor. As the motor receives the cooling air from the cooling fan, it disperses cold air into the environment. However, when the cooling fan breaks down, the motor can’t receive the cooling air. As a result, the AC starts to radiate hot air when you turn it on.

Bad Engine Coolant Sensor:

Another thing that’ll make your car overheat when the AC is on is the engine coolant sensor. The work of the engine coolant is simple; turn on the cooling fans at intervals. It does this by sending a signal to the control module switch. The work of the module switch, when it receives a signal from the coolant sensor, is to turn on the cooling fan automatically. But once the engine coolant sensor is faulty, your cooling fan won’t come on. In the end, it leads to your car overheating when you turn on your AC.

Related: bad ac pressure switch symptoms

AC Compressor Problem:

The AC depends on the compressor a lot to function. But the compressor draws quite a few energies from the engine. It puts considerable weight on the car engine. However, the moment the compressor starts to malfunction, it too much load on the engine. Then, the AC seems to draw power from the engine, cause it to overheat. If the compressor is the problem, you want to check the state of the car engine. If the engine is overheating, best believe that the compressor might be primary.

Related: AC pressure too high

Radiator problem:

The radiator is responsible for ensuring coolant and air flows freely. However, when substances like rust, dust, air, etc., build up in the radiator, it messes up the free flow of air and coolant. Consequently, what you’ll get is the engine overheating.

The symptoms of car overheat when ac is on.

When your car starts to overheat because you turn your car on, there are specific symptoms that’ll pop up to alert you. Some of these symptoms include

Change in Car Temperature:

The first noticeable sign is a swift change in your car’s temperature. Your car instantly goes from cold to hot the moment you turn on the AC. It could also be as worse as you perceive the smell of burning plastic or rubber. When that happens, whenever you turn on the AC, you should instantly turn off the AC. Then, drive your car to your mechanic to get it fixed.

Engine Shutdown:

Your engine has some preservation nature. When it starts to overheat because of the AC problem, it would instantly go off. Then, you’ll have to wait for it to cool down. Once it cools down, you can start the engine again. But that doesn’t mean you should keep using the car that way. The random engine Shutdown might be a result of your vehicle overheating from turning on the AC.

Acceleration and Speeding:

This problem also affects your car’s speeding. As a result of the overheating, your car would start to malfunction. You’d notice that this problem would start to mess with your car’s ability to adhere to your desired speed limit.


There is usually a cloud of smoke that oozes from the bonnet of your car. This steam is an indication that your car is overheating. Steams fly out from underneath your bonnet because of a fault in the coolant system.

Weird Noises:

Your engine compartment starts to make a noise that you’d consider as odd. Specifically, you’d start to hear a ticking sound from the compartment. It often occurs as a consequence of using engine oil that is overdue for change. When you fail to change it, friction occurs in the engine, leading to the ticking, weird sound. If this happens, you should dive into the engine to change the oil. Otherwise, please scroll through our recommended solution when your car overheats anytime you turn on the AC.

Related: How Hot Does a Car Engine Get

How to prevent car overheat when ac is on

Here are some of the tips you can deploy when you sense your car starting to overheat

Flush your radiator regularly:

If you have a mechanic, get them to flush your radiator. This method is effective because it washes the radiator. Your mechanic would get rid of the old coolant in the radiator. Then, the mechanic would flush the coolant to get rid of dirt. After that, your mechanic would add a new coolant into the radiator.

Replace Car Battery occasionally:

If your car battery is old, it could be making a fuss. Usually, you shouldn’t use your car battery for more than three years. Once it goes beyond three years, it would start to get weak. But since it needs to keep working, the battery would begin to overwork itself. When this happens, it negatively affects the health of your car. Hence, it starts to overheat. Try to change it to curb the overheating problem of your vehicle. If you’re not sure if it’s time to get your car battery changed, reach out to your mechanic for advice and a thorough check.

Regularly change the Coolant mixture:

Allowing the coolant mixture to stay in the coolant for long leads to overheating. To prevent your car from overheating, try to change your coolant mixture every two years. It would help if you change the coolant mixture after every 40,000m you cover. Don’t use a random product. Instead, reach out to your mechanic to recommend a product that’s best for your car brand. Also, use distilled water in the process rather than tap water. The benefit of occasionally changing your coolant mixture is that rust and corrosion won’t attack your engine and other parts of the car in general.

How to fix car overheats when ac is on

One of the easiest ways to fix car overheat when AC is on is to fix the causes. Hence, you need to figure out what the cause of the overheating is. Then, please fix it. Here are some of the practical steps you can take to fix car overheating.

Radiator Cleanse:

Is the radiator the cause of your car overheating when you turn on your AC? Well, it’s pretty easy to fix. Remember that the blockages, such as air, dirt, etc., are responsible for coolant breakdown. Hence, the simple fix is to clean the coolant/ radiator. Cleaning the coolant allows air and radiator to flow through the radiator freely.

Air Pressure Guage:

You need an air pressure gauge. This gauge is essential as it is a great way to monitor airflow. Once the airflow seems off, then you know it’s time to complain to your mechanic about the car. That way, you won’t need to wait till the car starts overheating.

Window Shades come in Handy:

Window shades are usually reinforced with UV heat resistance. So, when your car overheats, you need to shield it from further harm that the UV rays of the sun could cause. The truth is, with your heated car interior exposed to the sun rays, the rays would damage your car further. With window shades, the sun rays won’t easily penetrate your vehicle.

Park your car:

If you do not have window shades, find a shade. When the AC overheats the vehicle, you shouldn’t keep driving the car around, especially not during summer. The reason is, the sun’s rays would cause more harm to the vehicle. Hence, the next thing you should do when your car starts to overheat is park it under a shade. Look around for an area with good shades that would accommodate your car. Then, park your car underneath the shade and wait for the engine to cool off before you hit the road.

Related: Causes and Solutions of Car Starts then Dies

Wrap Up

Most of the time car overheats when AC is on, the AC might not be the culprit. Instead, other parts of your car that you have neglected might be responsible. For instance, rust might cover your radiator because you’ve not changed the coolant in a while. Other times, the car battery might be acting up because it is ageing. Either way, the easy way to get through with this is to take preventive measures and cater to your car’s health.

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