Car Shakes When AC Is On (Causes & Solutions)

If your car shakes when AC is on, this indicates an issue with the vehicle and requires attention without wasting much time.

A lot of people are of the opinion that this cannot happen unless the air conditioner’s compressor is having a problem. Meanwhile, various factors could be the cause of this, and these factors will be talked about in this article.

For proper understanding, knowing the name of engine parts is fundamental as well as how they work relatively with the air conditioner’s compressor.

The air conditioner’s compressor is a vital component of a vehicle. It is responsible for cooling the air inside a vehicle when it is hot; hence, it provides a comfortable environment for everyone in the vehicle. With this knowledge, it becomes a little bit easy to detect air conditioning systems failure and find ways to prevent it.

This article will explain the various reasons why a car shakes when AC is on, ways in which this problem can be solved, how much it will cost, and lots more.

Let’s begin!

How Can an AC Cause a Car to Shake?

When an air conditioner AC has low refrigerant, the compressor gets overloaded as it tries to cover up for the low refrigerant. This result in the entire system heating up, which reduces the cooling effect when switched on afterward.

Generally, suppose an air conditioner is switched on when the weather outside is extremely hot, although cool air is released from the vents. In that case, the air released through the vents is usually inadequate. This implies that the cool air released into the vehicle is not enough even with a working AC.

This is due to the fact that the quantity of refrigerant left in the AC is less than usual; hence, allowing warm air produced by the engine to get into the air conditioner through its condenser and mixing up with the little refrigerant remaining means the refrigerant becomes even less effective with almost no cooling effect.

Suddenly, the AC stops working even though its compressor is on.

Thereafter, the car starts vibrating or shaking due to the air conditioner’s poor performance as the compressor is overloaded and working more than it should. It also becomes very noisy inside the vehicle, which passengers, as well as drivers, find really frustrating.

However, all these signals will only show up mostly when the air conditioner has gone out, and starting the vehicle’s engine will not change the situation because regular air flows in, not cool air.

So, getting fresh air without coolant back into the vehicle will require topping up first. For this to be done, some quantity of new refrigerant will be used to replace the old refrigerant after it must have been taken out completely.

Related: Does Car AC Use Gas? (Answered)

Reasons a Car Shakes When AC Is On?

Reasons a Car Shakes When AC Is On

The air conditioning system is a necessary characteristic of all recently made vehicles. There are two major functions of the air conditioning systems. They are: creating low pressure to aid vaporization and increasing refrigerant pressure.

The vapor created absorbs the heat inside the vehicle, making it conducive for occupants while moving around.

The vehicle’s air conditioning system function is to make the interior of a vehicle cool. However, it is not always an easy process. The refrigerant has to be hotter than the normal room temperature before the heat can be transferred and circulate. This means that, at times, it is a more difficult process than others.

If a vehicle’s motor mounts and AC compressor are not working as they should, this will usually cause more pressure or a strain on the vehicle’s engine when using the AC. Hence the car starts to vibrate or shake.

Some popular factors that can cause a vehicle to start shaking when the air conditioner is switched on are:

1. Damaged AC Compressor

The most common reason a Car shakes when AC is on is a fullty AC compressor. When the compressor of the AC becomes faulty, it increases the workload on the vehicle’s engine, which can cause the car to shake or vibrate when AC is on. If the compressor of the AC is damaged or has a problem, it works with little effect.

The compressor cools the refrigerant before it is passed into the condenser. For this reason, if an AC compressor fails, it could overload the vehicle’s engine, and later on, the vehicle starts to shake when the AC is on, but the vehicle is idle.

When a vehicle idles for a very long time, it causes excessive drag. The cause of engine stalling is vibration while idle. Excess dragging while the air conditioner is working in a vehicle with power steering may cause the engine to stall more and the steering wheel shakes even more.

When the AC is working, increase the vehicle’s speed to reveal the vehicle’s problem. If a difference in pick is noticed, then replacing the AC is the next line of action.

2. Load on the Engine

Another reason a Car shakes when AC is on is too much load on the engine. When the AC is switched on, components like the air control engine and the idle speed become active through the vehicle’s engine.

Because of the high-tech insulation, Forced induction systems (compressors) put more workload on the engine and can cause the car to shake when such load exceeds a particular threshold.

If the load continues to increase, some components of the engine may start to wear out as time goes on. However, other factors may include, when a cooling fan becomes faulty or damaged and when the air conditioning system has an obstruction. If this is the case, take the vehicle to a nearby mechanic as soon as possible.

Defective fuel injector

A Defective fuel injector is another reason a car shakes when AC is on. The fuel injector is a very vital part of a vehicle’s engine. It works as a spray and controls fuel flow; it works with electronically controlled valves hence a fuel injector may close or open several times in a second.

If a fuel injector becomes faulty, it may add extra load on the vehicle’s engine, which can lead to the vehicle shaking while the AC is working.

3. Bad Spark Plugs

Bad spark plugs can also be a reason why a car shakes when AC is on. Spark plugs are responsible for generating electricity for an engine by causing a mixture of fuel and air to explode. Outdated or damaged spark plugs could be responsible for vibrations in a vehicle when the AC is switched on.

If the spark plugs of the vehicle can not deliver the speed or power required to ignite the engine, especially in the first instance, it could be a sign that there is a problem with the spark plugs that require a replacement to be fixed.

Also Read: Spark Plug Replacement Cost

4. Worn Out or Broken Motor Mounts

If a car shakes when AC is on, the problem could be from the motor mounts. If the engine mounts are broken, worn out, or misaligned, they can give the engine more work to do, and this can result in the vehicle shaking when the AC is switched on.

When the AC is switched on, the engine mounts are stressed. As the engine foundations or mountings wear out, the vehicle starts to shake and vibrate when the air conditioner is working. If the motor mounts should break down, the shaking becomes even worse.

5. Bad Throttle Position Sensor

Regulating the airflow going into the engine is a major function of the throttle position sensor. They monitor the extent to which the throttle valve or blade opens, which usually depends on how hard the accelerator is pressed down.

A bad throttle position sensor cannot regulate the RPMs of a vehicle, which leads to having inconsistent RPMs when the air conditioner is switched on. This can also make a vehicle shake or vibrate.

6. Loose or Disconnected Hoses

In certain instances, when a car shakes when AC is on, it could result from a disconnected or loose hose. When a hose gets disconnected or loose, it stops the proper flow of the vehicle’s conditioning system.

If the vehicle is put in a situation where it does more hard work due to climate changes, it will likely vibrate and shake when the AC is switched on.

7. Dirty Throttle Body

A dirty throttle body can be the reason your car shakes when AC is on. The throttle body’s duty is to maintain the air-flowing system of a vehicle’s engine. The throttle body passes air into the engine, which makes it get dirty in no time.

This accumulation of dirt in the engine can result in the engine not being able to get adequate airflow. Consequently, when the AC is switched on, the vehicle vibrates due to its inability to get sufficient airflow.

Also Read: Car AC Smells Like Vinegar (Causes & Solutions)

How to Fix Car Shakes When AC Is On

How to Fix Car Shakes When AC Is On

To fix a vehicle that shakes or vibrates when the AC is working can be a little bit difficult because the first thing that needs to be done is to investigate the cause of the vibration or shaking.

A very common cause of vibration or shaking when a vehicle is idle, and the air conditioner is working is when the throttle body is dirty. Hence, if the throttle body is cleaned, the vehicle may stop shaking or vibrating when the AC is working.

A dirt-filled throttle body may not be the sole reason a vehicle vibrates while the AC is working. For this reason, it is necessary to investigate why the vehicle shakes. If a dirty throttle body is a problem, then following this procedure should help the situation:

  • Shut off the vehicle’s engine.
  • Lift up the bonnet
  • Carefully inspect the throttle body for dirt and particles
  • Ask another person to turn the key to the ON” position without starting the engine.
  • Ask the person to slowly press the accelerator.
  • Get a clean cloth and use the same to wipe the throttle body till it’s clean.

Step 1: Shut off the Engine

Before trying to repair a vehicle that shakes or vibrates when the AC is switched on, it is required that the engine be shut off completely.

Step 2: Find the Throttle Body Under the Hood

After shutting off the vehicle completely, lift the car bonnet and find the throttle body. If the throttle body is seen to be dirty, then it requires cleaning.

Step 3: Leave Your Car Key Turn “ON” Position but Don’t Start

Ensure not to start the engine of the vehicle; just let the car key stay in the “on” position in the ignition. If the engine ignites, cleaning the throttle body will not be possible.

Step 4: Press the Accelerator Smoothly

The accelerator should be pushed slowly to properly clean a vehicle’s throttle. Do not push it till it gets to the surface; a little push suffices.

Step 5: Clean the Throttle Body Using Throttle Body Spray

A throttle body spray can be used in any vehicle maintenance store. The spray should be applied to the throttle body; thereafter, get a cloth and wipe it clean.

When cleaning the throttle body, it has to be done with serious care and caution. There is no need to be in haste because it takes ample time to clean a throttle body.

In most situations, the reason a vehicle vibrates when the air conditioner is working is due to a dirty throttle body; hence, if a vehicle’s throttle body is dirty, then these steps provided will assist in fixing vibrations and shaking in a vehicle when the air conditioner is on.

Car Jerks When AC Is On

Jerking most especially when the AC is on is an indication that there is an issue with the power versus load available. The air conditioner becomes an additional or extra load. However, the problem may be caused by something else, not the air conditioner. Always ensure the fluid level is well gauged and inspect the vehicle.

Conclusion – Car Shakes When AC Is On

Car shakes when AC is on is a problem a lot of drivers go through. The information and tips provided in this article help identify the problem when it happens, its causes, and how it can be fixed. Some people are fond of waiting and hoping that everything returns to normal after a while. This is a big mistake that is seriously discouraged.

If a car shakes when AC is on, it could be due to various reasons. The important thing that should be done is to fix this problem immediately after it is discovered to avoid worsening the situation. Always ensure that the air conditioning system works as it should and has no effect on the vehicle’s load.

Scott Greene is a seasoned automotive technician for over 5 years and has been deep into advanced automotive diagnostics for a couple of years. He Loves writing about Automotive Diagnostics and Repair, Trouble codes, Buyer guides for various car parts and accessories, and lots more. 

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