Car air conditioning (A/C) systems run on the power generated by the engine’s crankshaft. While this power allows the A/C to supply cold air to the cabin, it also forces the engine to work harder. If your vehicle’s cooling system is in good condition, this extra load shouldn’t be much of an issue. But if your cooling system is on the fritz, then your vehicle’s engine temperature will likely spike, prompting the powertrain control module (PCM) to turn off your A/C whether you want it to or not.
Why Your A/C Turns off When the Engine Is Hot
Here are possible reasons why your A/C turns off when your vehicle’s engine gets too hot:
Low Coolant Levels
When coolant flows through the engine, it absorbs heat and delivers it to the radiator. Over time, this coolant can evaporate and cause the engine to overheat if it isn’t topped off regularly. When this happens, your engine will overheat, causing your A/C to shut off.
This is why it’s important to change your coolant according to your manufacturer’s recommendation, which is usually every 30,000 to 100,000 miles.
Clogged Radiator
Over time, dust, dirt, and other debris can build up on the radiator’s fins and prevent them from blowing air across the coolant to cool it down. The coolant’s temperature remains high, causing the engine to overheat and the A/C to shut down.
A clogged radiator can also be caused by dirty coolant, corrosion in the cooling system, and mineral deposits in the radiator. Inspect and maintain your vehicle’s radiator regularly to avoid these problems.
Faulty Radiator Fan
Inside the radiator, you’ll find thin metal fins that blow on the coolant to cool it down, effectively redirecting the hot air outside the vehicle. Malfunctioning radiator fans won’t be able to cool down the hot liquid, causing the engine to overheat.
Stuck Car A/C Thermostat
The A/C thermostat is a valve that opens and closes at specific temperatures, controlling the flow of coolant. When the engine is cold, the thermostat stays shut, preventing the coolant from flowing to the radiator. When the engine gets hot, it opens, allowing the coolant to reach the radiator and begin the heat exchange.
If the thermostat is stuck in the closed position, the coolant won’t be able to reach the radiator. Engine temperature will rise and cause the A/C to shut down.
Blown Head Gasket
Low coolant levels can also point to a bigger issue: a blown head gasket. When a head gasket fails, the coolant can leak into the cylinders and evaporate into white smoke. This can cause coolant levels to drop, resulting in an overheating engine. In some cases, the coolant can also leak into the engine oil, damaging the engine’s bearings.
Cracked Radiator Hose
If your vehicle is low on coolant, be sure to inspect the radiator hoses as well. A worn radiator hose can develop holes or cracks, which can eventually lead to coolant leaks. You’ll have to replace the radiator hose with a new one to prevent further damage to the engine.
Dirty Air Filter
An air filter prevents dirt and other debris from entering the engine’s combustion chamber. It’ll accumulate dirt over time, so it’s meant to be replaced every 30,000 to 45,000 miles. Failure to do so will prevent oxygen from entering the combustion chamber, resulting in a messed up air-fuel ratio. This can cause the engine to overheat, prompting the PCM to shut down the A/C.
Malfunctioning Coolant Temperature Sensor
As its name suggests, the coolant temperature sensor is responsible for measuring the coolant’s temperature. It relays this data to the PCM, which will then adjust the fuel injection, ignition timing, and other conditions accordingly.
In some cases, a faulty coolant temperature sensor might think the coolant is cold when it isn’t. When it sends the “cold” signal to the PCM, the PCM will unnecessarily adjust the combustion process, resulting in an overheating engine.
Damaged Air Intake Temperature Sensor
High engine temperature can also be a symptom of a damaged air intake temperature (AIT) sensor. An AIT sensor is responsible for monitoring air temperature and helping the engine adjust to different conditions.
Although it rarely happens, a faulty AIT sensor can prevent the PCM from adjusting the air-fuel mixture correctly. This can cause the engine to idle roughly and overheat.
What To Do if A/C Turns off Due to High Engine Temperature
Before anything else, you should find a safe place to park. Next, check the temperature gauge on your dashboard. It’ll display how hot or cold the engine coolant is. If it reads hot, then this means your engine is likely overheating, causing the PCM to turn off the A/C. If the gauge doesn’t read too high but the A/C still shut down, then there might be an issue with your cooling system.
Is It Safe To Drive a Car if the A/C Shuts off Due to High Engine Temp?
Your vehicle might run for a while, but we strongly advise against driving your car until the issue is resolved. Driving your car when the engine is overheating can significantly damage the engine. In some cases, it might even cause a fire. Look for a safe place to park, and call for help as you wait for your vehicle to cool down.
How To Stop the A/C From Turning off Due to High Engine Temp
The answer to this is pretty simple. You have to keep up with your manufacturer’s recommended service interval. Change your coolant when necessary, and regularly inspect the radiator, hoses, and other cooling system components.
Keep Reading: Related Posts
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.
