Whether you notice a car shakes when AC is on or vibrates when AC is on, both occur for defective car cooling systems.
Cars can start shaking when AC is on and idling anytime if air conditioning supporting components are not operating properly.
Most car owners blame the car AC compressor for the car vibrating or car shaking when ac is on, but there can be various reasons why your car shakes when the AC is on.
Here, you are going to know what are the causes of car shaking when AC is on and what to do when your car vibrates when AC is on.
What Causes Car Shakes When AC Is On
Broken or wear out engine mounts, bad air conditioner compressor, and defective fuel injector are the main causes why a car shakes when AC is on. While the car shakes or vibrates, you can hear the noise at close notice.
Some possible causes why a car shakes when AC is on:
- Faulty AC Compressor
- Load on Engine
- Defective Fuel Injector
- Bad Spark Plugs
- Broken or Worn out Engine Mounts
- Faulty Throttle Position Sensor
- Faulty Mass Airflow Sensor
- Hoses are Loose or Disconnected
- Dirty Throttle Body
1. Faulty AC Compressor
A damaged or faulty car AC compressor is the major cause of car shakes when AC is on. An AC compressor is also a necessary part of a car cooling system.
The AC compressor increases the temperature of the refrigerant through the compressor before sending the right level of refrigerant to the condenser.
The engine is the primary energy source of a car. So, when you turn on the air conditioning, the engine begins to run the car air control motor, which starts draining the car AC compressor.
When your car’s air conditioning compressor fails, it can produce an excess load on the car engine and eventually make your car shake when AC is on.
To detect the faulty AC compressor that makes your car vibrate when ac is on, you need to observe the car air conditioner’s components properly. Check your car’s air conditioning for overcharging because overcharging AC is not applicable for vehicles.
If your car’s air conditioner has been overfilled, You should remove the Freon from your car right away. Avoiding overcharged AC and faulty AC compressors is essential to address the car’s shaking issue.
Related: Car Overheats When AC Is On
2. Load on Engine
Your car’s air conditioning system is connected to the car’s engine. As you already know, the air conditioning compressor is the primary component of the cooling system, which is connected to the engine.
When the pressure goes above 400 PSI, the AC compressor starts putting excess pressure on the engine, and this load on the engine makes your car vibrate when ac is on.
If the car engine is getting pressure consistently, your car’s other parts can also get hurt or break down.
When your car’s air conditioning compressor is put on the engine, you can feel the vibration in the steering wheel instantly.
A car air conditioning load on the engine shakes your car when you turn AC on and brings some component issues in the car.
Excessive pressure on the engine also won’t let your car AC not blow cold air. Regular maintenance of your car’s air conditioning compressor can avoid load-on-engine issues.
3. Defective Fuel Injector
The fuel injector is a vital part of the engine in a vehicle. The fuel injector’s job is to spray fuel into a car’s engine using electronically controlled valves, which can open and close many times a second.
The engine needs to be fuel-run effectively and also when you turn AC on.
If your car’s fuel injectors can’t function effectively, it strains the engine because of the lack of fuel and eventually makes a car shake when AC is on.
Even a faulty fuel injector can make your car rough idle when AC is on. Every time you go to the service center to maintain your car, you should check the fuel injector with a professional.
Often, a malfunctioning fuel injector needs to be replaced, and you should replace it to keep your car engine away from further issues.
4. Bad Spark Plugs
The spark plug produces power for your engine by creating an explosion and air/fuel mixture.
Improperly functioning spark plugs cause a car to shake with AC on. A damaged spark plug increases the vibrations of your car while idle and AC is on.
Spark plugs also get old after a certain time of use. Between every 80,000 and 100,000 miles or each year, the spark plugs need to be replaced with new ones.
If your car’s spark plug can’t provide the engine ignition’s power or speed, especially during the first power generation, it might have an issue. In this case, you will need to replace the spark plug.
5. Broken or Worn out Engine Mounting
The engine mount is an essential component that holds your car engine and the car’s transmission in the right place.
Car manufacturers bolted the vehicle engine and transmission together, and the engine mounts keep holding them together and prevent any shaking.
As you know, turning on the air conditioning in a car creates a load on the engine and puts a lot of strain on the engine mount.
Because of a lot of strain, the engine mounts can wear out or even break. But, a broken or worn-out engine mount can’t tolerate the load strain; that’s why your car shakes when you turn your AC on.
With a bad engine mount, you can experience more issues with your car AC; the common one is car AC clicking noise.
To fix car engine mounting, you need to go to an auto repair shop, and you have to tell them your car vibrates when idle and AC is on; they will replace the engine mounting.
In most cases, if your car jerks when ac is on for broken engine mounting, the engine mounting needs to be replaced too.
6. Faulty Throttle Position Sensor
A Throttle position sensor (TPS) job is to monitor the air intake of an engine.
The throttle position sensor monitors how far the throttle blade (or valve) can be open, which is determined by how far down the accelerator pedal has been pushed.
The car’s bad throttle position sensor cannot control the RPM (Revolutions per minute).
That’s why if your car has a bad throttle position sensor and you turn the air conditioner on, then your RPMs do not remain constant for the bad TPS. Hence, the car can vibrate when idle, and AC is on with unstable RPMs if you notice this issue in your car.
7. Faulty Mass Airflow Sensor
The mass airflow sensor (MAF) is a major component of a car’s electronic fuel injection system.
Car shaking with AC on is a common symptom of a bad mass airflow sensor. Cars commonly jerk and vibration in idling because of a faulty mass airflow sensor.
When you go to an auto repair shop to fix why your car vibrates when you switch on the AC, the mechanic always checks your car’s airflow sensor because a faulty mass air flow sensor can be another cause of the car shaking when the AC is on.
8. Hoses are Loose or Disconnected
Those of you don’t know what houses are in your car. The hoses are the cooling system’s (Air conditioner) weakest structural component, and the hoses are made of flexible rubber.
For many reasons, your car’s hoses can be loose or disconnected from the engine mount. When hoses are disconnected from the mount, the car shudders when AC is on.
Whenever you inspect loose or disconnected hoses, you should tighten and connect the loose hoses again.
9. Dirty Throttle Body
The throttle body maintains the air-flowing system in your car engine. You will find the throttle body between the car air cleaner and the engine’s intake manifold.
Whereas the throttle body is an air-passing component that can get dirty quickly, car engines can’t get sufficient airflow.
So when your car engine cannot get airflow properly, it makes your car vibrate when you turn on the ac. By cleaning the dirty throttle body and fixing car shakes when AC is on.
That is all; You just know the possible causes of why your car shakes when AC is on. You should check each cause before you replace your car’s air conditioning for the car vibrating. Your experience also helps you to notice why your car shakes when AC is on.
Some car owners ask Reddit questions about specific car models, like why cars shake when AC is on Toyota Camry or BMW vibrates when AC is on, but car shaking causes are the same for every car.
How To Fix Car Shakes When AC is on
Fixing a car that shakes when AC is on requires several testing of components in the car, which makes it difficult to address this problem.
As you have seen, all the possible causes of cars vibrating when AC is on. Hence, you need to specify the main cause of your car’s shaking and fix that component to stop your car from shaking.
Knowing which component of your car makes it shake is necessary before fixing the issue.
Among various possible causes of car shaking when AC is on, the most common cause is considered a dirty throttle body.
That’s why here I’m going to give you the step by step on how to fix car shakes when AC is on if the throttle body is dirty.
Follow these steps to fix a car that shakes when AC is on:
Step 1: Shut Off The Engine
Before trying to fix a car that shakes when AC is on, you must ensure the engine is shut off.
Step 2: Find The Throttle Body Under The Hood
When your car shuts off completely, now you need to open up your car hood and locate the throttle body. You will see your throttle body is dirt that you need to clean.
Step 3: Leave Your Car Key Turned “ON” Position, But Don’t Start
Make sure you do not start the car engine, just leave the car key “on” position in the ignition. If you start the engine, you won’t be able to clean the throttle body.
Step 4: Press The Accelerator Smoothly
Whenever you clean the throttle body of your car, you have to push the accelerator slowly. Avoid pushing to the surface; just a little press is enough.
Step 5: Clean The Throttle Body Using Throttle Body Spray
You will find throttle body spray in any auto shop after getting throttle body spray and extra cleaning clothes.
Now, spray the throttle body cleaner or spray on the clean cloth and start rubbing on the throttle body carefully to clean it.
When you clean the throttle body, you have to be careful. Do not try to hurry because cleaning the throttle body takes time.
In many cases, your car vibrates when AC is on because of the dirty throttle body, so if your car’s throttle body is dirty, then this is how you can fix car shakes when AC is on.
Can A Bad Fuel Pump Cause Your Car To Shake?
A bad fuel pump causes your car to shake, even when your car is idle. Not only the fuel pump but there are also many different reasons why your car is shaking.
A bad fuel pump, dirty fuel injectors, bad airflow sensor, and faulty O2 sensor also can be the reason why your car shakes.
Why Does The Car Shake When Accelerating?
Your car shakes when accelerating because of damaged motor mounts or dirty spark plugs.
Typically when the car’s engine creaks, a vibration is produced but damaged or loose engine mounts cannot absorb that, and eventually, you experience your car shaking when accelerating.
You can’t fix a motor mount; you have to replace the motor mount and stop your car from shaking when accelerating.
Why Is My Car Misfiring When The AC Is On?
Your car misfiring is related to the AC compressor because the engine’s air conditioning gets torque.
When you turn on the AC, the compressor clutch gets activated. The engine drops some RPM when you start the AC, and the car’s actuator opens to allow more air into the engine.
Therefore, if the AC compressor is not working properly, your car can misfire when you turn the AC on.
Why Does My RPM Go Up And Down While AC Is On?
Many engine components provide a significant amount of load on the engine, especially when you turn AC on.
For instance, the AC compressor produces huge pressure or load on the car engine, which actually most commonly causes the car’s RPM to go up and down while AC is on.
A failing AC compressor, Bad belt, or overfilled AC system are also the reasons why your car RPM goes up and down while AC is on.
What Causes Rough Idle When AC Is On?
Sometimes your car can get rough idle if you turn the AC on, and car owners often face this problem.
In most cases, your car is at a rough idle when the AC is on for a dirty throttle body, faulty condenser fan, old spark plugs, worn-out engine mountings, and faulty IAC valve.
If your car is rough idle when AC is on, check these components with AC on to diagnose which one is behind rough idle.
By cleaning most of these components of your car properly, you can get your car rid of rough idle when AC is on.
Car shakes when AC is on is a common issue with vehicles, and various reasons and components in your car that make your car vibrate when AC is on.
Excessive load on the engine, bad air conditioning compressor, and faulty fuel injector are the most common reasons why a car vibrates when AC is on and idling.
Everybody knows that it will cost you high money and a huge amount of time when it comes to the issue of a vehicle. That’s why first detecting what causes car shakes when AC is on is always a great idea.
After discovering why your car vibrates when AC is on, you shouldn’t wait to see if this issue will go away automatically.
You have to try to fix the car shaking issue by yourself, and if you don’t have the proper experience, you need to go to an auto shop to fix it. Proper and regular maintenance of your car is always important.
Take your car to a professional if your car shakes when AC is on, don’t wait too long because it won’t fix the issues.
How is it going?
I’m Meraj Sarker. I am a Car Mechanic and a student of Automobile Restoration here in Florida, USA. I’ve been studying automotive for around 9 years now. So you can rely on my recommendation. For me, studying and getting knowledge about automobile it’s really fun and entertaining. I will help you to get solutions for your car through this website. If you need any help let me know.