Why Is My Car Temperature High When AC is On?

Why Is My Car Temperature High When AC is On?

Note: As an amazon associate I may earn a small commission from qualifying purchases if you click to amazon from my site and choose to make a purchase.You can read my complete affiliate disclosure for more details

Why Is My Car Temperature High When AC is On?

The temperature in your vehicle’s engine is indicated by the temperature gauge fitted on your dashboard.

There are many reasons why many car owners ask why is my car temperature high When AC is on?

This may result from coolant leaks or even a faulty water pump. This gauge effectively shows the temperature that your engine coolant is operating at.

From this gauge, you will be able to tell if your coolant is hot or cool. The gauge also shows when the coolant is normal.

If it overheats, you will also be able to see that from your temperature gauge.

This is an important dial that should always remain functional. A faulty temperature gauge can occasion great misery and loss.

In other instances, the temperature gauge reads cold. This remains so until the engine runs for a few minutes.

After running for a few minutes, there are instances that the gauge may still read cold.

You will need to check if it’s functioning, and this may not be a DIY activity.  You will require a qualified mechanic to have your temperature gauge checked.

Why Is My Car Temperature High When AC is On?

The temperature gauge may also read zero if the thermostat controlling the gauge remains open. An open thermostat may cause overcooling of the engine and will need to be replaced.

What Is the Remedy If Your Temperature Gauge is High?

When you realize that the temperature gauge on your car’s dashboard reads high, the simple conclusion is that your car is overheating.

Overheating is a very serious problem that you can never ignore.

Indeed, there is no reason in the world that you should drive an overheating car unless your life is in danger.

Therefore, you may first need to bring your car to a safe stop. If this happens when your Air-conditioning is on, shut it off and open any windows that may be closed.

When you switch off the AC and open windows, but the problem persists, try to turn on the heater to the highest it can get.

If, after all this, there seems to be no improvement, you will need to switch off the engine.

After switching off the engine, open the hood and wait for the vehicle to cool down on its own.

On no occasion should you ever attempt to open the radiator while the engine is still hot? .

This can cause severe burns on your face as the coolant spills over from the radiator. It may be time to seek professional help from a trained mechanic.

The role of a temperature gauge is so essential that without one, you should never drive a car. This is because you will not be able to tell the temperature in the car’s engine.

Without this knowledge, you can cause a lot of damage as the engine can overheat without your knowledge and lead to significant damage.

As you drive, make sure that you have a functional temperature gauge for the sake of safety. CLICK HERE to check current prices on Amazon Prime

But for you to identify the problems related to overheating when you turn the AC on, continue reading the article to the end.

How Do You Know If Your AC Increases The Temperature In Your Car?

With that in mind, it could be very frustrating when driving your car in summer but can’t turn on the AC.

This is doubly frustrating if you know that the AC is operational, but turning it on will cause overheating in your car.

Many car owners experience many heating problems when they have their AV turned on. This is more frustrating since the AC is supposed to do the opposite: cool the car.

When the car is hot, there are many components whose functionality is at risk. In addition to this, a hot car is not a place anyone would wish to be during summer.

Read on to know the factors that occasion overheating when the AC is on.

To be sure that it’s the Air Conditioner causing heat in your car, you will only need to turn it on. After a few minutes, the engine, seats, and air in the car will be hot.

After you turn it off, it will take a few minutes and have the temperature restored to normal. To know the culprits of the high temperature when you turn the AC on, read on.

Can a Worn AC Compressor Cause My Car To Overheat?

Worn AC compressor comes as the major cause for AC overheats. As long as the car overheats when the AC is turned on and cools when the AC is turned off.

This could be the reason behind your problem.

Why Is My Car Temperature High When AC is On?

Peradventure this is what you are experiencing; your AC system could be faulty. The AC compressor will be the first suspect in this case.

Let’s look at the functions of the AC compressor first so that we will understand the issue at hand.

Through the serpentine belt, the Air-conditioning compressor links to the engine. As soon as the engine turns on, it will deliver power. This power comes through the AC compressor.

AC compressors are connected to the engine by a belt that turns a pulley. In instances that the pulley is worn out, bent, or is on a bad bearing requires more force from the engine to turn it.

This extra load occasions more work from the engine when AC is turned on. Consequently, the engine will start to overheat due to the overload.

Inside the car, the excess heat will be experienced.

Therefore, when you have a damaged AC compressor, it results in an overloaded engine that will dictate overheating in your car.

The solution to this will require swift execution. On realizing that your AC is causing your car to overheat and you suspect a case of a damaged AC compressor, turn off the AC instantly.

If you take too much time before turning it off, the engine is vulnerable to self-destruction through melting from the inside.

When you turn off the AC, the car should start to operate normally again.

If you have positively diagnosed the compressor as the problem, you only need to buy another one and have it fixed.

If there are other defective parts, ensure that they are replaced to get the best services from your new compressor.

Does Dirt or Old Coolant make my car overheat when I turn on AC?

The general make-up of coolants is to enable them to last long without any need to be replaced. However, this may not remain the case indefinitely.

If your coolant has become dirty or old, it may not perform its essential function of cooling the car.

When a coolant fails in its functions, it leaves your car vulnerable to overheating.

This will be the time that you will have to change it. A coolant that no longer cools the car has lost its purpose and must be replaced and disposed of.

When the AC is turned on, this problem is compounded. This is because AC demands more power from the engine.

As a result, the engine will strain more and produce more heat in the process.

Consequently, it will not be hard for you to notice that your car overheats when the AC is turned on.

It’s simple to solve this particular problem. The coolant needs to be replaced. You will need to replace it with a coolant that will meet the demands of your car.

It will also need to meet the performance standards of your car. CLICK HERE to check current prices on Amazon Prime

There is no other way to solve this problem.  Again, the coolant needs to be replaced when it starts to show rust-like color in the radiator.

Another reason you will need to replace the coolant is to protect other car engine components from corrosion and rusting.

Can Defective Cooling Fans cause my car to Overheat when I Turn on AC?

The answer to this question is yes. Defective fans cause overheating in your car when AC is turned on. The car should not overheat when idling.

However, if you turn on AC and it overheats while idling, your fans can be defective.

The car’s cooling system consists of a radiator. The radiator is effective in drawing excess heat from the car through the water.

As the water flows through the radiator fins, it is cooled and pumped back to the engine by the water pump.  

This is a repetitive process that will ensure that your engine is kept cool. If the car is idling, the cooling fans will fan enough air to cool the water that is in circulation.

However, if the fans fail, the water will not be cooled, and it will be pumped back to the engine still hot.

This will continue to exacerbate until the heat gets to the point that it will be felt in the car/ when the car is moving, it will lose much power.

If you establish this as the cause of your overheating in the car, you will need to replace your cooling fans or have them checked to be repaired. In most instances, they are repairable.

An electrical disconnection may also cause this behavior as the fans may not have the required electric power to function.

Therefore, if your car overheats when you turn on the AC while it’s idling, check if the fans are functioning. In most cases, this will be the problem that you will need to address.

What Happens When There Is A Damaged Or Blocked Radiator?

When you notice that your fans are functional but your car is still overheating, there is another cause.

If the car heats while idling and the fans are still fanning, you could be facing a radiator problem. Your radiator can be damaged or even clogged.

Radiators get clogged many times. This results from sucking a plastic bag and other elements that may not allow the normal function of the grille.

When the grille is blocked, normal airflow is blocked. When the air that is flowing in the radiator is deficient, there will be a resultant overheating.

In this instance, the turning on of AC will cause the car to overheat.

As implied before, AC places more demands on the engine, and if the engine is already struggling to keep itself cool, this will occasion more heating.

Why Is My Car Temperature High When AC is On?

For you to identify and solve this problem, you will need to first look through the grille.

Find out if there is anything that is blocking the airflow. In many instances, you will readily discover that there are evident damages to your radiator.

It may also be too dirty or too old. If this describes the condition of the radiator, it will scarcely exchange heat.

Therefore, it will not cool the water, and the water will be flowing back to the engine while still hot.

In addition, corrosion will also build up on the inside of the radiator. When this happens, there is an excellent reduction in the cooling performance of the radiator.

You will need to deal with this problem. See if there are any blockages and ensure that they are unblocked.

If the radiator is damaged to the extent that it cannot be repaired with much success, it will be time to purchase another.


When you notice that your car overheats as soon as the AC is turned on, there are many things that you will need to put into consideration.

In many instances, the problem will have stemmed from the cooling system that is in your car.

The cooling system that comprises the radiator must perform its functions effectively to ensure that the car is kept within standard temperatures.

On the other hand, the engine may be the cause of the problem, but you will need to do the required groundwork to identify the cause.

In most instances, these are problems that you can quickly fix without seeking any professional help.

However, if you try all the DIY stuff and nothing seems to work, seek professional help since you may have misdiagnosed the problem.

Recent Posts