How To Fix Rough Idle When AC Is On

How to Fix Rough Idle When AC is on

One of the most irritating car issues is rough idling. Drivers find this problem frustrating as it can cause problems with starting, poor performance and even lower fuel economy.

So, if your notice that your vehicle is idling rough when you turn on the AC and returns to normal when you turn off the AC, you’re in the right place.

In this article, we’re going to let you know why your car is idling roughly and how you can fix it when the AC is on.

The Procedure Of Fixing Rough Idle When The Ac Is On

The leading cause of rough idle when the AC is on is a dirty throttle body. Depending on your vehicle’s year of manufacture, make, and model, you will discover that fixing the AC is simple. Most issues with older cars can usually be resolved by turning off the throttle.

But for the newer vehicles, it is recommended to fix the car while the AC is on. If you fix a new car model with the AC off, you may still experience rough idle.

Here is the procedure of fixing rough idle when AC is on:

  1. Open the car hood.
  2. Open the throttle body.
  3. Have a friend or colleague turn the key to the “On” position, but don’t start the car engine.
  4. Ask the helper to gently press the accelerator.
  5. Next, spray the throttle body cleaner onto a rag.
  6. Then, use the rag/cloth to position the throttle bore and blade.

You should take care when cleaning the throttle body as even a small mistake could cause serious damage and harm. Mishandling the throttle blade can make the throttle blade to upset the throttle base.

Fixing the car when the AC is on is not simple. If you are unable to detect the problem, you can use a scanner to diagnose the issue before you fix it.

Car Dies When The Air Conditioner Is On: Why?

Sometimes the car can suddenly die when the air conditioner is turned on. When If this happens during a jam, it can be very frustrating. These are some possible causes.

A Faulty Fuel Pump

One of the main culprits that can cause your car to stall is a faulty fuel pump. If the fuel pump is bad and the AC is turned on, it can make the car to stop suddenly or even rough idle.

This is because a clogged fuel filter won’t filter the contaminants from gasoline, which may increase and slow down the flow of fuel. In the long run, the engine won’t receive enough fuel, which will make the car stall.

Low Battery

If your car’s electrical system is working well, then the air conditioning places an extra load on your battery. As a result, the battery gets drained quickly as the alternator isn’t producing enough electricity; hence, the regulator has nothing to manage.

You should make sure that your alternator is functioning properly and that the battery is fully charged. If not, the car will stall when you turn on the AC as there will be little power.

Bad Alternator

Additionally, if the alternator is bad, it may not work as needed. Bad alternators may not be able to fully charge the battery. It doesn’t matter whether the engine is running or not.

And when you turn on the AC, you will be putting more pressure on the bad alternator. This can cause the car to die.

Faulty Idle Air Control Valve

The procedure of fixing rough idle when the AC is on

A faulty Idle Air Control Valve can also make the engine to stall. The IAC valve regulates engine idle depending on the engine load.

For instance, if the IAC valve fails to move to the ideal position for the load the AC compressor enforces on the engine while at idle, the car stalls.

Note that a bad Idle Air Control valve may leave the car without a source of air to keep a proper idle. This can also cause engine stalling.

Bad Air Compressor

If the air compressor is damaged, it will also affect the engine’s operation when the AC is turned on. The AC needs a lot of generating power to run. Thus, if the AC is not supported well, it may not function as needed.

This could cause the compressor to stop running and may even cause it to become stuck. As a result, a lot of debris may be sent into the AC system, which may lead to severe damages to the compressor and other parts.

It can cause the car to stop working or it could even cause it to stop altogether. Therefore, you should replace a bad air compressor as quickly as possible.

Dirty Throttle Body

Another reason for your car stalling may be because of a dirty throttle body. A dirty throttle body can cause your engine to stall. It may be unable to function properly if it is full of carbon. This could cause the car to stall.

You can either clean the throttle body yourself or hire a professional to do it for you. You may need to replace the throttle body if it is damaged or worn.


Ac is a vital part of your car. Not only does it provide cold air when it is hot, but it can also heat the car when it’s cold. As a driver, it is your responsibility to make sure that all components and the vehicle are working correctly.

Make sure that your AC is working correctly and doesn’t affect the vehicle’s power.

Besides, you can fix any car issue that may be directly or indirectly linked to the AC. Whether your AC is causing a rough idle or making your car stall, you can fix it using the methods that we’ve discussed above.

You can hire a mechanic if you find the process difficult.

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