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Car Overheat When AC Is On: Reasons Why, Causes, Symptoms

by Jordan Harris
Car Overheating Causes

Driving in the summer is peaceful as long as you are comfortable in your vehicle and have the air conditioning on. However, have you ever experienced a situation when the temperature gauge went above the safe range as soon as you put on the air conditioner? If so, you would want to know why your car overheats when AC is on, wouldn’t you?

If you ever find the source of the issue, a solution will naturally come to mind. You must be familiar with some systems in your car before you can comprehend this. As a result, we will learn about the causes of car overheating when the air conditioner is on, the signs and symptoms of this problem, and finally how to resolve it.

Car Overheating 

Nothing makes a motorist feel hot under the collar like an overheating automobile. The issue is that, if you’re not an auto expert, you might not be able to identify the exact cause. This might make you perspire even more. Numerous factors can cause engines to overheat. 

Generally speaking, it occurs when the cooling system is malfunctioning and heat cannot exit the engine compartment. A leaking cooling system, a problematic radiator fan, a malfunctioning water pump for car, or a clogged coolant hose could be the cause.

An overheating engine shouldn’t be left unattended, regardless of the cause of the issue. Your engine can endure severe, if not irreparable, damage. The most frequent causes of an overheating car are listed below. The same applies to other scenarios, such as when your car is running hot but not overheating, in addition to your car is smoking but it’s also not overheating.

Car Overheating Causes

Here are some of the main causes of your car overheating:

1. Cooling System Failure

Failure of the cooling system is a major contributor to engine overheating. The engine’s combustion chamber can reach 4,500 degrees Fahrenheit. Yet, the cooling system pulls heat away from the engine and out to the atmosphere. Your automobile may overheat if the cooling system is malfunctioning, such as if there is a coolant leak.

Your summer road trip could end abruptly if you neglect to maintain your cooling system, which could lead to severe damage or even full engine failure. It’s not a matter of whether the cooling system will fail. Rather, it’s a matter of when it will fail if regular maintenance isn’t performed in accordance with the OEM maintenance schedule.

2. Malfunctioning Radiator

Simply put, the radiator, which draws heat away from your car’s engine, is a crucial component of the cooling system. Therefore, your engine could easily overheat if something goes wrong with the radiator, such as dust or debris buildup. In this case, considering a radiator flush cost might be a good idea.

Otherwise, be mindful of the radiator repair cost or the radiator replacement cost. Your engine can overheat, leaving you stranded on the side of the road, so it’s important to change the vehicle’s coolant in accordance with the OEM maintenance schedule. To find cooling system issues early on, drivers can also conduct a visual assessment of the radiator, hoses, and belts.

Car Overheat When AC Is On

3. Faulty Hoses Or Belts

Belts or hoses that aren’t functioning properly are often to blame for overheating engines. The engine’s cooling, air conditioning, and charging systems rely heavily on the vehicle’s belts and hoses. Belts transfer power from the front of the engine to accessories that must be driven. These include the air conditioning and charging systems, and fans. 

While this is happening, coolant is transferred between the engine, radiator, and heater core via radiator and heater hoses. Regularly inspecting your car’s belts, hoses, and fluids may assist guarantee that it stays adequately cooled and in good condition for many miles to come. 

4. Low Engine Oil

By reducing friction, motor oil helps to regulate the temperature of your car’s engine. As a result, engine overheating may occur if your car’s oil level is low or leaking. Oil ensures that the internal engine parts are kept lubricated and ensured to move freely. Lack of lubrication leads to friction, which generates excessive heat and may result in engine failure.

5. Faulty Thermostat

The thermostat is susceptible to failure, just like any other auto component. The thermostat controls the coolant and aids in preventing engine overheating. Therefore if it malfunctions, it could be problematic for the engine. Unusual temperature swings and/or coolant leaks are additional symptoms of a malfunctioning thermostat in addition to overheating.

6. Water Pump Failure

The cooling system’s coolant is essentially kept moving by the water pump. The water pump circulates the coolant, which is heated by the engine, through hoses to the radiator. The coolant then circulates back to the engine to restart the cycle once the radiator has removed the heat from it. 

Issues with a water pump, like a leak, could make an engine overheat. Steam flowing from the radiator and coolant leaks under the front of the car are two other common indicators of a failed water pump. Therefore, make sure you’re wary of the symptoms of a bad water pump, as well as the water pump replacement cost.

Signs Of Car Overheating

Car Overheat When AC Is On, Signs Of Car Overheating #1: Temperature Gauge

Depending on the model, your automobile can have a coolant temperature gauge or a warning temperature lamp. If there is an unusual rise in engine coolant temperature, both components will illuminate as a warning indication.

To make sure that either of the two components functions as intended, regularly check for coolant leaks. It’s a good idea then to find out what causes a coolant leak.

Car Overheat When AC Is On, Signs Of Car Overheating #2: Car Physically Heating Up And Strange Odors

If your car is unusually hot and you can smell burning rubber or plastic, it may have overheated. The scent can indicate melted plastics or gaskets. The majority of the engine in your car is made of metal. But it also includes plastic and rubber seals. 

Consequently, an overheated engine typically has an odd, “hot” odor. Check to see if you have a coolant leak or if you also notice an oddly sweet smell. After parking, check the ground for coolant puddles to prevent leaks.

Car Overheat When AC Is On, Signs Of Car Overheating #3: Ticking Sounds From Engine Bay And Engine Shutting Down

Engine oil loses its viscosity if it is used for longer than is advised. This will result in it losing the ability to carry out its job in the engine. Due to the lumps that will develop after such an event, friction will begin to arise. The ticking noises may denote this underlying issue. 

Whether the air conditioner is on or not, it shuts down automatically as a preventative measure in overheated cars. Once the temperature has dropped, you will be able to restart the automobile.

Car Overheat When AC Is On: Main Causes Why

On a hot day, your car’s air conditioning system might be keeping you cool and comfy just fine. But your engine might be experiencing something else entirely. You may be perplexed about the potential causes of the problem if you have the AC blasting and see that the temperature gauge on your engine is rising. 

A malfunctioning fan switch, motor, or cooling fan is one of the most frequent causes of engine overheating when the air conditioner is on. Other factors that contribute to overheating include a faulty engine coolant sensor, a loaded air conditioner compressor, a broken water pump, and clogged AC condenser fins.

Following is a list of some of the most typical reasons why your car overheats when the AC is on. In case you’re absolutely perplexed as to why this happens these might help you in pointing out the cause of the issue. 

Car Overheat When AC Is On, Causes #1: Faulty Engine Coolant Sensor

The purpose of the engine coolant sensor is to track the internal working temperature of the engine. It communicates the vehicle’s temperature to the Electronic Control Module (ECM). The ECM among other things decides when to activate the cooling fans for your engine. 

If your engine coolant sensor is broken, it will give the ECM an incorrect internal engine temperature reading. Your car may overheat as a result of the fans not operating when they should. 

Car Overheat When AC Is On, Causes #2: Overloaded AC Compressor

The AC compressor is a crucial component of the AC system in your car. Its task is to pressurize the liquid refrigerant in your engine, and it does this by utilizing the power from the engine’s output shaft. A defective air conditioning compressor places rotational stress on the engine shaft, which causes your engine to overheat. 

Car Overheat When AC Is On, Causes #3: Malfunctioning Water Pump

Another potential culprit is a bad water pump. It maintains your engine’s internal working temperature by circulating a mixture of coolant and water throughout it. Your car won’t have any functioning cooling systems without a water pump. This causes your engine to get unusually hot. 

Car Overheat When AC Is On, Causes #4: Faulty Fan, Fan Switch, And / Or Fan Motor

One of the most frequent reasons why your automobile overheats when the air conditioning is on is faulty engine fans. When you turn on your car’s air conditioning system, it’s not these fans that blow cool air into your face. Instead, they monitor the airflow in your automobile and alter the speed of their fan to cool the engine as necessary. 

Overheating issues can occur if the engine cooling fan is broken, the fan blades are bent out of shape, or the fan switch that activates the fans is malfunctioning. It can also happen if the fan motor that drives the fans is faulty. 

Car Overheat When AC Is On

Car Overheat When AC Is On, Causes #5: Clogged Water Condenser Fins

While AC condenser overload can also overheat your car, the condenser fins are more likely to be at fault. For those of you who are unfamiliar, the AC condenser is where hot refrigerant cools off before being routed throughout your engine. 

The condenser’s fins are prone to becoming clogged with dirt and debris. When that occurs, the AC condenser won’t operate as effectively. This will limit how much the coolant mixture can be cooled. As a result, when the AC system is turned on, your car’s engine will become too hot.

Engine Hot AC Off 

Almost all drivers are aware of how important an engine is. As a result, a driver can feel concerned and perplexed when they see the Engine Hot AC Off warning. An Engine Hot AC Off warning is not unusual, despite the fact that it could cause a lot of problems for your car. What does an Engine Hot AC Off warning mean? What sets it off? 

The Engine Hot AC Off warning light shows that the electric cooling fan in the automobile isn’t working properly. This is causing the engine to run hot or overheat. Notably, the leading cause of engine mortality globally is overheating. Therefore, if your engine overheats, you should act right away.

Along with running effectively in the event of a fan failure, the AC uses a lot of energy that the engine might not be able to produce. As a result, your air conditioner can shut off to lessen the burden on the engine caused by excessive engine temperatures.

The Engine Hot AC Off warning could also be brought on by a leaking cooling system. Other causes may include low engine coolant levels, a damaged water pump, or improper component wiring (the latter might even cause other issues like your temperature gauge not working).

If this warning arises, stop right away to evaluate your engine’s condition. Your car’s engine propels it, and repairing or replacing one can be quite expensive. You shouldn’t keep driving when your automobile is overheating or otherwise putting unnecessary strain on the engine.

Temporary Fix For Overheating Car 

The possibility of irreparable engine damage may be decreased if you can take action to cool your engine before it overheats to the point of failure. But first, you need to be aware of the signs of overheating. Follow these instructions and call the closest repair facility as soon as you notice the engine overheating.

To lessen the strain on the engine, shut off the air conditioner right away. Then, set the dial to the highest heat setting. In order to prevent the engine from overheating until you can stop in a safe place, this can assist draw heat away from it. You might feel a little warm yourself, but a few minutes of discomfort is nothing compared to expensive engine repairs.

Stop the car, pull over, and turn it off. At least 15 minutes should be given for the engine to cool. As the engine cools, the temperature indicator should return to a normal range, so keep an eye on it. Plan to get your overheated engine examined while you wait (and keep an eye on the gauge). Make an assistance call to a friend, a tow truck, or your neighborhood repair shop. 

If coolant is low, a simple top-off could protect your engine and keep it from overheating while you wait for repairs. If a coolant hose is obstructed or a broken radiator fan or water pump is the cause of your problems, this step won’t be very helpful. For information regarding your vehicle’s coolant reservoir tank, refer to your owner’s handbook.

If your car isn’t being towed away, you should safely start your engine again and head to the closest auto repair facility. As you drive, keep an eye on the temperature gauge. Pull over and allow the system to cool if it rises once again.

Car Keeps Overheating: Fixing An Overheating Car

Depending on the cause of the issue, having your car fixed at a shop may be expensive, particularly if a new compressor is required. Don’t assume anything, though; you might be able to identify and fix additional issues that are causing your car to overheat when the AC is on.

Car Overheat When AC Is On, Fixing An Overheating Car #1: Coolant System Flush

Even before your vehicle exhibits overheating symptoms, it is a good idea to routinely check the coolant system. Your car’s air conditioning system may suffer long-term damage if sediment and sludge accumulate in the hoses and drains. These unwanted components can be removed from the coolant mixture using an appropriate solvent.

Car Overheat When AC Is On

Car Overheat When AC Is On, Fixing An Overheating Car #2: Cleaning The Radiator

The radiator is a crucial component of your automobile’s air conditioner. An obstructed radiator could be the cause of your car overheating when the AC is on. The radiator’s straightforward operation makes it vulnerable to compromise. Since it’s crucial to maintaining the engine’s cooling, any issues with it should be fixed right away.

The constant exchange of water and coolant might be halted by an obstruction. It may just take a few minutes to check and clean the radiator fins of a significant obstruction or silt accumulation. The radiator’s internal pipes may also need to be checked. A good coolant system cleaner will do the trick.

Car Overheat When AC Is On, Fixing An Overheating Car #3: Refilling The Radiator With Antifreeze Or Water

The car radiator must have the right amounts of water and antifreeze in order to operate effectively. It will heat up and put a straining rotational load on the engine of your car if it isn’t kept cool enough. Refilling the radiator’s low water and coolant levels keeps it cool and prevents heat buildup. 

Heat buildup can result in hot spots developing in your engine. The engine may experience permanent harm as a result, including engine component swelling and distortion. In order to prevent long-term problems in the future, it is essential to make sure your radiator has the proper amounts of coolant and water. 

Car Overheat When AC Is On, Fixing An Overheating Car #4: Servicing The Air Conditioning System

When your car overheats, the root cause may occasionally be too complex for you to identify on your own. This is mainly because of how the coolant system is designed to function. Perhaps you are unable to check the inside of the radiator pipes, change a drive belt, or find a coolant leak because you are lacking the necessary tools.

If you can’t find the problem despite your best attempts, having your automobile serviced will offer a guaranteed solution. A qualified technician can correctly identify the problem, offer advice, and carry out the necessary repairs.

Car Overheat When AC Is On: Conclusion

An automobile that is overheating can be dangerous in addition to being unpleasant. It is crucial to realize that your car’s AC system is a crucial component and needs to be properly maintained. Regular maintenance can go a long way toward reducing overheating problems. This includes checking for leaks and making sure the AC refrigerant level is correct.

It’s crucial to keep in mind that when the AC is on, there can be underlying problems that can lead to overheating. These problems can be a faulty thermostat, a broken radiator fan, or a clogged radiator. Therefore, it is recommended to consult a trained mechanic if you experience overheating when the AC is on. 

Additionally, when the AC is on, driving practices and environmental conditions can also cause overheating. For instance, prolonged high-speed driving or hot-weather stop-and-go traffic. These conditions might place greater stress on your car’s air conditioning system and cause overheating.

As a result, it’s crucial to take safety precautions including avoiding hazardous driving situations, parking in the shade, and regularly checking your car’s coolant levels. In conclusion, you should implement preventative actions to ease pressure on your car’s AC system.

Preventing car overheat when the AC is on necessitates a mix of correct maintenance, locating, and resolving underlying problems. Follow these steps and you can keep your car running smoothly and prevent the aggravation and risk of overheating.

FAQs On Car Overheat When AC Is On

What Causes A Car To Overheat 

A car may overheat for a number of reasons. These include a damaged thermostat, low coolant levels, a cooling system leak, a malfunctioning radiator fan, a broken water pump, or a blocked radiator. It is important to act quickly to prevent overheating from seriously damaging engines.

How Much To Fix AC In Car 

Depending on the problem, repairing a car’s air conditioning might cost anywhere from $100 to $4,000. Simple fixes, such as replenishing the refrigerant, can be about $100, whereas more significant fixes, such as replacing the compressor, can run over $1,000. To get the best price, consult with a certified mechanic.

How To Fix AC In Car 

The best way to fix a car’s air conditioning depends on the problem. But typical fixes include charging the refrigerant, changing a damaged compressor or condenser, or fixing a leak in the system. It’s preferable to have a skilled mechanic identify and resolve the problem. Performing routine maintenance can stop AC issues from arising.

How Long Does It Take A Car To Cool Down 

The ambient temperature and the size of the car determine how long it takes for a car to cool down. Larger automobiles may take up to 15 minutes to cool down, compared to 5-10 minutes for smaller cars. Sunshades, window tinting, and airflow can all speed up cooling.

How Hot Does A Car Engine Get 

An automobile engine can become so hot that harm can result. Most engines typically operate in a temperature range of 195-220 degrees Fahrenheit. The temperature gauge will show an overheating problem if it rises above this range. Prolonged overheating should be immediately treated because it can seriously harm engines.

Can Low Oil Cause Overheating 

Yes, low oil levels can result in overheating. Engine oil aids in heat dissipation and lubricates the moving elements of the engine. Because the engine won’t be properly lubricated if the oil level is low. Hence, friction will increase and heat will build up. This may eventually lead to engine overheating and possible damage.

Should Radiator Fan Turn On When AC Is On 

The radiator fan should activate when the air conditioner is running to assist in dissipating the heat it produces. The air that the fan blows over the radiator cools the coolant that is flowing inside. By doing this, the engine is kept from overheating. A bad fan motor, relay, or sensor may be to blame if the fan doesn’t operate when the AC is on.

Will A Bad AC Compressor Affect The Engine 

Unreliable AC compressors can, in fact, harm engines. The engine may become overheated as a result of added stress if the compressor seizes. In addition, leaking refrigerant from the compressor can pollute engine oil and harm the engine. To avoid causing harm to the engine, compressor problems must be fixed right away.

How To Cool Down A Car Engine Quickly   

Turning off the AC and cranking up the heater will help a car’s engine cool down more rapidly. Leave the ignition on when you stop and turn off the engine. To improve the airflow, raise the hood. Prior to starting the engine again, wait ten to fifteen minutes. If the overheating continues, it is essential to get professional assistance.

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