Hey, Why Is My Car Overheating When I Turn The AC?

Hey, Why Is My Car Overheating When I Turn The AC?
If the cooling system of your vehicle is not operating to maximum performance, the air conditioning system will add additional heat to the front of the radiator and add extra load to the engine. When the AC is running, this extra heat and load will cause a marginal cooling system not to pull enough heat away from the engine and cause it to overheat.

Is Your Car Overheating When You Turn The AC?

The car is overheating after turning the air conditioning on because of a faulty coolant temperature sensor, clogged radiator, and condenser fins. Less commonly, it can be an issue with the condenser fan relay or fan control module.

If your car's air conditioner is causing your vehicle to overheat, it is crucial to address this issue promptly. Failure to do so could lead to safety hazards and costly repairs.

Consider the assistance of a skilled professional to diagnose and fix the issue accurately. This approach helps keep your car in excellent condition, ensuring your safety. Remember, neglecting a seemingly minor issue could cause more significant problems in the future, which could have been avoided with timely attention and maintenance.

Let's Get To The Bottom Of It!

  • Q: Is your AC starting cold and then gradually getting warmer?

    The condenser is a part of the air conditioning system that sits before the radiator. Its job is to help remove heat from the freon and coolant by allowing air to flow across it. When the cooling fan turns on, it helps pull this air through the condenser and radiator to cool everything down. However, if it fails, it can diminish airflow. The AC and engine temperature can rise and cause problems if there isn't enough airflow.

  • Q: Do you hear a rubbing noise from the cooling fans when you turn the AC?

    The cooling fans help to cool down the engine and the air conditioning system by moving air across the radiator and condenser. If the bearings in the cooling fan motor wear down, the fan can rub each other, make noise and cause damage to the fan shroud.

  • Q: Is the AC only cooling the cabin when you drive at highway speeds?

    The condenser fan draws a lot of power and is controlled by a module using a relay. The contacts in the relay can get damaged due to the high current draw of the fan motor, preventing voltage from passing through and turning on the fans. The improved airflow when driving at highway speeds allows the condenser and radiator to keep the engine cool. Therefore, the air conditioning works appropriately through natural means.

  • Q: Is the car's AC not working and displaying a "check engine" light on its dashboard?

    Modern vehicles use a module to control engine fan speeds and maintain proper engine and air conditioning temperatures. If the module malfunctions, the engine control module will detect it, turn on the check engine light, and disable the AC system to prevent the engine from overheating.

All related issues checked?

Find Professional Help

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Hey, Why Is My Car Overheating When I Turn The AC?

Vehicle Health Inspection Proof

Explore the following typical inspection results that show a potential cause for the symptom and select the one you believe is similar to your vehicle's issue.

Faulty coolant temperature sensor

The proof image shows the failing coolant temperature sensor located in the water jacket. Replacing this sensor should fix the problem with the air conditioner and the coolant leak.

A customer brought in their vehicle, concerned because they heard a gurgling noise from the engine and saw coolant leaking out of the overflow bottle. They also mentioned that their air conditioner stopped working before the gurgling noise started. In addition, they did not notice the temperature gauge showing any issues.

During a test drive, the technician did not notice any issues with the customer's concerns. However, during a vehicle health inspection, the technician noticed the coolant was low, but nothing related to the customer's problems.

The technician requested authorization for additional diagnostics, and the customer agreed. The technician used a specialized scanner to check for error codes, but none were present.

They then ran the vehicle with the air conditioner on high for about 30 minutes, using an infrared thermal scanner to check the water passages around the temperature sender. Finally, they compared the readings from the scanner to the live data on the scanner, which showed a temperature of 195°.

However, the infrared thermal scanner showed that the temperature on the water jacket had increased to 225°, and the cooling fans did not come on. This confirmed a defective engine coolant sensor that needed to be replaced.

Does the issue look like this? if not accessible your shop will document it

Typical Fixes to Address the Cause(s)

The following chapters bases themselves on experiences from our auto repair shop; we'll describe related problems' causes and fixes.

"Coolant sensor replacement" fixes "Faulty coolant temperature sensor"

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Sometimes a problem is more challenging to describe than it initially looked like. If you are not sure your problem is described by this article, please find below similar vehicle symptoms, which might describe better the issue you are experiencing.

Other things your auto repair shop might talk about:

Car overheats when ac is on. Coolant mixture. AC compressor. Car cooling system. Faulty water pump. AC compressor overload. Fan switch.

Is Overheating AC
Your Issue?