Why is it that a car overheats when AC on? There are two key components in the air conditioning system that are at play when this happens:
- The AC compressor
- The AC condenser
These two parts are not wholly independent, but like other engine parts are intricately interconnected. This being the case, if either of the above parts aren’t working properly, the engine ends up having to work much harder, therefore generating more heat and possibly even overheating.
3 Common Causes
There are three principal causes of air conditioning issues in your car, all of which can ultimately lead to the AC causing overheating.
1) The compressor is not turning properly
The job of the AC compressor is to compress the refrigerant before it’s fed to the cooling system. When there is a fault in the compressor and it’s proving harder to turn as normal, then the engine and its serpentine belt that turns the compressor will work harder to compensate. As it does, it generates more heat, eventually leading to overheating.
2) The cooling system is faulty
Once the refrigerant reaches the condenser, the engine fan blows it over the condenser fins. When the fins get clogged, however, this means that the system again has to work harder to get the same amount of refrigerant through, leading to overheating.
3) There’s a problem with the car’s temperature sensor
When your car has automatic climate control, it depends on accurate temperature sensors. When these are not working, sometimes giving a higher reading than reality, the AC will try to compensate, leading to overheating in the system.
Tips to Fix
Fortunately, there are several simple solutions to this problem:
- Ensure your mechanic uses the correct and compatible refrigerant for your car. Certain refrigerants won’t work properly in certain models, so ensure your mechanic is using the correct one.
- Check the radiator for debris. When the car is switched off and cool, remove the radiator cap and clean it, and check the rest for any debris clogging it up.
- Flush the coolant system. Air can become trapped in your car’s coolant system, which is a big contributing factor to overheating. Flushing it will remove any trapped air.
- Ask your mechanic to use a multi-meter to make sure proper voltage is reaching the AC compressor. The system may not be working properly if the wrong voltage is getting through.
- To fix the condenser, you need to make sure the fins are clean and unclogged at all times. Have your mechanic check the fins regularly to ensure there are no blockages.
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Does a bit of extra heat matter?
Your engine is a finely tune piece of engineering made up of many, many moving parts. Overheating is a sign that one of those parts is not working optimally. It’s important to keep your eyes open for the signs we mention above, and if at any time you feel the AC is causing overheating, get it checked by your mechanic immediately.
When it comes to a car’s engine, procrastination only means more expensive bills down the road!