Hey, Why Is My Car Overheating When I Turn The AC?
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!
The temperature-sending unit is a part of your car's engine that tells the engine control module (ECM) how hot the engine is. It's located in the water passages before the thermostat and works with the coolant temperature sensor to regulate the air-fuel mixture. The temperature sender also sends a signal to the instrument cluster, which helps turn on the cooling fans when the engine gets too hot. But if the temperature sensor reads the wrong temperature, the engine might overheat without the temperature gauge indicating its actual value.
The radiator is crucial to your car's cooling system. It has a storage tank with fins attached to each side of its core. If the cooling system is neglected, particles can build up and clog the radiator cores, restricting the coolant flow. If this happens, the coolant cannot go through the cores and dissipate heat, causing some cores to remain cooler than others. This can be seen with a thermal imager.
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.
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.
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.
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.
Find Professional Help
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
- Clogged radiator
- Clogged condenser fins
- Faulty cooling fans
- Faulty condenser fan relay
- Faulty fan control module
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.
1/6Typical 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.
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Vehicle Symptoms
Below are just a few examples of typical Symptoms and Fixes your car might be 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.