Why is my car overheating when AC is on while the engine is idling?

Driving in summer without AC is difficult. Every car comes with an air conditioner or heater to adapt to the temperature seasons throughout the year. Most people face a common issue regarding their car overheating when AC is on and idling.

The car overheating when ac is on can result in many different casualties. When the engine is hot, it boils water under the radiator and bursts out from it in case of a damaged cap. In this way, most of the electrical equipment installed in your car is at risk.

If you are facing this problem, then do not worry. Many people in your surroundings also face the same issue, but we are here to guide you through all the possibilities and solutions which can save you a few bucks.

Knowing the problem before consulting with the mechanic always comes in handy and saves your time and money.

Few possible issues that your car overheating when ac is on and idling

Issue in radiator

Radiator plays an essential role in the cooling system of an engine. It keeps the engine’s temperature moderate and keeps it in one piece when traveling in your car. But one of the problems behind car overheating when AC is on is a clogged radiator.

Radiators pass cool air to the engine and keep the temperature regular when the temperature goes up. If the radiator is damaged and the air is blocked, it will cause the car overheating and when ac is on and idling.

To prevent your car from overheating while using ac, you can get your car’s radiator serviced from a service shop if it is blocked by dirt. If the radiator’s fins are damaged, and there is no possible way to repair it, you must get your car’s radiator replaced.

Faulty Fan

Radiators are equipped with exhaust fans on them. Suppose your car’s engine is a big one, i.e., more than 1.6 liters. It will be equipped with two fans. Whereas, if the car has a smaller engine, there will be a single fan.

When the engine is started, one fan turns on to provide a cold air supply to the engine, which keeps the temperature of the engine moderate. When ac is turned on, the second fan is also turned on as the engine needs more air supply because it is bound to run both car and the ac.

The reason behind the car overheating when the ac is on, and idling can be a fault in the second fan. You can quickly check the fans of your radiator if they are working or not. If one fan is not working, you can check for a faulty fuse in the fuse box or get a new fan installed on your car’s radiator.

Compressor overload

As your car’s engine has to run to make your car work continuously, the compressor is also working continuously to keep your ac in working condition. The compressor and engine of your car are somehow similar to each other.

Sometimes, the compressor of ac puts a lot of load on the engine, which makes the engine do extra work and ultimately overheat even when idling. Most of the time, it happens when you install a multifunctional compressor in your car, which takes a lot of energy from your engine.

To overcome this problem, you need to install a compatible ac compressor to match the power consumption and output in your car. If the compressor is the compatible one, then your engine might be weak and cannot manage it.

Gasket Issue

Engine overheating can be due to a mechanical fault in your engine. Overheating due to a mechanical fault in the engine does not often come. It usually occurs due to some negligence routine of the driver, i.e., not checking the water level in the water pump.

If you are negligent in maintaining the water level, it will result in overheating the engine, and you will face serious issues. Car overheating also occurs if you have recently got your engine overhauled, and everything is working fine, but the car overheats and ac blowing hot air. It is due to a fault in the gasket.

You can quickly get your car to your mechanic, and if the issue is in the gasket, you can replace the gasket with the compatible one or install a double gasket.

Faulty sensor

Sometimes, everything in your car is working as it should, but the problem is in the thermostat sensors of your vehicle. So, before taking everything out, check these sensors and see if they are in a normal condition or fault

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Frequently Asked Questions

Yes, oil is one of the essential components when your engine is running as it lubricates all the internal parts of the engine. When the oil level is low in the engine, it causes friction and overheating the engine.

If the level of coolant is low, then your car’s cooling system will not be able to provide coolant to all the tunnels of the engine where it is required. So, it is necessary to keep the coolant level to the maximum.

It can be due to several reasons, for example, the radiator fan is not working, the compressor is overloading the engine, the gasket is faulty, or a clogged radiator.

This issue occurs due to a faulty radiator fan or blockage in the radiator. When the car is traveling, the engine somehow gets the required air, but when it is idle, it starts to heat up, and the radiator cannot provide cold air.

When the AC starts giving hot air, it means that the cooling system fan is faulty. Due to this reason, the condenser and engine get hot and start giving hot air.


A car needs a small amount of care to keep functioning correctly. When you forget to fulfill the necessities of your car, for example, checking the coolant level, checking engine oil, and checking the radiator, when you regularly maintain your car, you will never face any significant issues while using your car.

But, if you face ‘car overheating while ac is on’ issue, you can check for the mentioned possibilities and consult a good repairing company.