car ac

Why does my car overheat when the A/C is on?

When the summer heat is above average, all you need is to turn on your AC and enjoy a cool breeze from your car. Unfortunately, this is not always the case.

Sometimes you turn on the A/C, and the car overheats.

If you have found yourself in that situation, you know how frustrating it can be. In this article, we will discuss some of the major reasons why your car will overheat when you turn the AC on. We will also share with you a solution for each case.

Let’s get started.

1. Worn AC CompressorWorn AC Compressor

This is one of the major reasons why your AC will overheat. This is especially if the car overheats only when the AC is turned on, and temperatures go down when the AC is turned off.

If this is the problem you are experiencing, then the AC system is faulty, and the AC compressor is the main reason for this change.

The AC compressor connects to the engine through the serpentine belt. When the engine turns on, the belt starts to spin. It delivers a power AC compressor.

An AC compressor with worn-out seized pulley, bent, or bad bearing will put ab extra load to the car engine. This makes it work harder when the AC is turned on.

The overloaded engine starts to overheat. And this is what brings the excess heat you experience in your car when the AC is turned on.

In the case of a damaged AC compressor, the overheating comes from an overloaded car engine.


If you notice this kind of heating, quickly turn off your AC. If you don’t, the engine might start melting and destroying itself from the inside. Turning off the AC will make the car engine operate normally.

If the compressor is the problem, go ahead and buy a new compressor. Replace the defective parts to get the best performance from your car.

The following are the best compressors you will find in the market. But the one that fits over your car AC system.

ACDelco 15-20941 GM Original Equipment Air Conditioning Compressor and Clutch Assembly

          Perfect for all General Motors Vehicles

          Original factory component

          Reliable, durable, and high quality

Click here to check the latest price and buy it from Amazon now.

UAC CO 29002C A/C Compressor

          OE replacement

          Add your car model on Amazon to check the fit

          Perfect performance

Click here to check the latest price and buy it from Amazon today.

2. Dirty Or Old CoolantDirty Or Old Coolant

Coolant can last for a long time without the need for replacement, but eventually, you will need to change it. When the coolant becomes old or dirty, it stops cooling your car as a coolant should.

This means your car engine will start to overheat if the coolant is not doing a good job.

The problem becomes worse when the car AC is turned on. The AC requires some extra power from the engine. This means that the engine will produce some more heat.

That’s why you will notice that your car will begin heating when the AC is turned on.


The solution to this particular problem is simple. Replace the coolant. Get a coolant that will give you high performance for your car.

This is the only way you will solve this problem.

Another reason you will need to replace the coolant is to protect other car engine components from corrosion and rusting.

BMW 82141467704 Coolant/Antifreeze is the best coolant you will find in the market. If you wish to get, the best cooling effect flushes your current coolant and replace with it. Click here to check the coolant and buy it from Amazon now.

3. Defective Cooling FansCooling Fans

If your car overheats when idling after turning on the AC, the fans could be the blame.

A car cooling system has a radiator – a system of fins behind the car grille. The role of the radiator is to draw the excess heat away from your car and flows through the fins. This is how it keeps the engine cool.

When the car is idle, the cooling fans should be working to provide enough cool air circulation into the system. So, when the car is idle, and fans aren’t working, you start feeling excess heat.


If this is the case, you might need a new cooling fan, cooling fan motors, or electrical connection for the fans that are affected.

So, when you notice your car overheating when the AC is turned on, and the car is idle, check the fans. This is likely to be the problem you are dealing with.

4. Damaged or Blocked Radiator

In the case, your cooling fans are functioning perfectly, but the car still overheats when idle, then the radiator could be the problem.

In most cases, you will find that your radiator is blocked. This happens if your car sucked a cardboard sheet, plastic bag, or other elements that could block the grille, it blocks the airflow. You won’t have enough air flowing through the radiator.

If this happens, the car will overheat even when an AC is turned on.

why does my car overheat when the ac is on


To deal with this problem first check through the grille. See if anything is blocking the air passage.

Sometimes you will find that the radiator is damaged, too old, or dirty. As a result, it doesn’t exchange heat properly.

With time corrosion also build up on the inside fins that slow down coolant flow. As a result, the cooling performance is reduced.

In short, to deal with this problem, you need to check any damages or blockages on the radiator.

Read Also: How to bleed off an overcharged AC: Steps That works

Parting Shot

If your car overheats when the AC is turned on, chances are there is a problem with the car cooling system or engine.

Check for signs of any of the four problems we have shared with you in this article. Fix them. But if nothing seems to change, seek professional help. Get help from a qualified mechanic. 

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Scroll to Top