How To Fix Rough Idle When AC Is On

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. This problem is challenging to drivers as it can lead to starting problems, poor car performance, or even reduced 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 of the older car issues are usually solved by removing 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. Access the throttle body.
  3. Have a friend or colleague turn the key to the “On” position, but don’t start the car engine.
  4. Request the helper to slowly press on the accelerator.
  5. Next is to spray the throttle body cleaner on a rag and or cloth.
  6. Finally, use the rag or cloth to lean the throttle blade and bore.

Clean the throttle body carefully as a slight mistake can cause harm and severe damage. 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. However, if you cannot detect the issue, you can use a diagnostic scanner to find out before fixing the problem.

Car Dies When The Air Conditioner Is On: Why?

Sometimes, the car may die suddenly when you turn on the air conditioner. When this happens in a traffic jam, you may have a long day. Here are some of the things that may cause this to happen.

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.

For this reason, you should ensure that the alternator is working properly and 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. A bad alternator may not have what it takes to keep the battery fully charged. 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 will result in the car dying.

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 controls the engine idle, depending on the load enforced on the car engine.

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 also leads to 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.

Also, this may cause the compressor to be seized and prevent it from running. 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.

In the end, it will affect how the car operates and stall it. 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. If the throttle body is full of carbon, it may fail to function as needed and put a lot of pressure on your engine. This may end up making the car stall.

However, you can clean the dirty throttle body or hire a mechanic to help you out. And if the throttle body is damaged or worn out, you may have to replace it.


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. Therefore, it is your duty as a driver to ensure that the vehicle is working properly and all parts associated with it.

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.

If you find the procedures challenging, you can also hire a mechanic to help you out.