When your vehicle shakes when the air conditioner is turned on, it’s an indication that there’s an issue that has to be addressed. The majority of people believe that this occurs only when there is a problem with the AC compressor.
However, it might be the consequence of a number of factors, which we will address later in this article. To fully comprehend this, you must first learn the names of the engine components and how they interact with the AC compressor.
The vehicle’s air conditioner compressor is an essential component. In hot weather, it cools the inside air of a car, creating a comfortable atmosphere for the passengers.
With this knowledge, you’ll be able to predict when AC systems may fail and how to avoid them.
Understanding the Basics of Car Air Conditioning
Before we dive into the reasons behind the shaking, it’s essential to understand how a car’s AC system works.
The AC system is a complex network of components that work together to cool the air inside your vehicle. The primary components include:
- Compressor: This is the heart of the AC system, responsible for compressing refrigerant and pumping it through the system.
- Condenser: This component is responsible for cooling the hot refrigerant gas that comes from the compressor.
- Evaporator: This is where the cold refrigerant gas is pumped, allowing it to absorb heat from the air inside the vehicle.
- Refrigerant: This is the substance that changes state from liquid to gas as it circulates through the system, allowing it to absorb and release heat.
The AC system is powered by the serpentine belt, which is driven by the engine. When the AC is turned on, the compressor kicks in, and the system starts to circulate refrigerant.
This process requires a significant amount of power, which can put additional strain on the engine and other components.
How Does A Car AC Work?
In a car AC system, the refrigerant goes through a compressor. It is compressed and the heat generated during the operation of a compressor allows it to get hot. During this process, pressure increases in the sealed system.
The hot gas is transferred under pressure from the compressor to the condenser by means of an expander or turbine vanes attached to which then transfers its heat out into the atmosphere.
Once the job of the compressor is done then this high-pressure gas flows into an expansion valve where it gets reduced into liquid form with help of absorbing more heat but only at lower pressure.
Now that low-pressure liquid flows back into the receiver-dryer where moisture captured in low-pressure liquid gets removed so as to provide cool essential oil desired for the operation of the compressor.
After this, a capillary tube is attached to the receiver-dryer which further transfers cool essential oil into the evaporator where it absorbs heat from air being blown by the car’s fan for supplying cool air inside the car cabin.
Once all these things are done then finally that cool air is passed through several vents in the car and you feel fresh and relaxed again after a hard day at work for a drive home. All modern vehicles are equipped with electronic expansion valves.
Common Symptoms
Identifying the symptoms can help narrow down the cause of the problem. Here are some common signs that your car may exhibit when the AC is on:
- Vibration at Idle: The car may shake more noticeably when idling, which is often the first sign that something is wrong.
- RPM Fluctuations: The engine’s RPM may fluctuate when the AC is on. You might notice the RPM needle moving up and down on the dashboard.
- Reduced Cooling Efficiency: The AC may not cool as effectively as it used to. It can be a sign that the AC compressor is struggling or that there is another issue affecting the system.
What Causes Car Shakes When AC Is On?
#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.
#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.
Diagnosing the Problem
If your car shakes when the AC is on, it’s important to have it diagnosed by a qualified mechanic as soon as possible. They can use specialized tools and their expertise to pinpoint the exact cause of the problem.
Here are some steps a mechanic might take to diagnose the issue:
- Inspect the AC system visually: This involves checking for any obvious signs of damage, leaks, or loose connections.
- Check refrigerant levels: A mechanic will use a gauge to measure the pressure and temperature of the refrigerant system. Low refrigerant levels will be evident.
- Listen for unusual noises: A mechanic will listen carefully for any whining, grinding, or other unusual sounds coming from the compressor or other AC components.
- Use a diagnostic scanner: A diagnostic scanner can read the codes stored in the car’s computer, which can provide valuable information about any electrical problems affecting the AC system.
How to Fix Car Shakes When AC Is On
As we have seen above, various factors can cause the car to shake when the AC is on. Therefore, the way to fix the issue will depend on what causes the shaking.
The most common cause of AC that makes cars idle rough is a dirty throttle body. In this case, follow these steps:
- Open the vehicle hood
- Check the throttle body carefully
- Ask a partner to turn the car key to the “ON” position. They should not start the engine.
- Ask the perform assisting to press the accelerator slowly
- Spray a throttle body cleaner on a clean cloth
- Use the cloth to clean the throttle body carefully
If a dirty throttle body was the cause, then you will have fixed the issue. In some cases, this problem would be due to a faulty AC compressor. In this case, you will be required to change and replace the AC compressor.
FAQs.
Q: What Causes Rough Idle When AC Is On?
There are various reasons why the vehicle could rough idle when the AC is on. The leading causes of rough idling are a dirty or faulty AIC valve, faulty condenser or cooling fan, dirty throttle body, damaged or old spark plugs, and worn-out engine mountings.
Some will need you to just clean to solve these problems, and others require you to replace the parts entirely.
Q: How Do You Fix a Rough Idle When AC Is On?
Fixing a rough idle when AC is on will depend on the cause. The most common cause is a dirty throttle body. In this case, you can solve the issue by cleaning and unclogging the throttle body.
If old and worn-out spark plugs cause it, the solution will be replacing them with new ones. At times the AC itself could be faulty, and it needs replacement.
Therefore, it is advisable to visit a professional mechanic who will help find out what the actual cause is, and then you will get to know how to fix it.
Q: Will a Bad AC Compressor Affect the Engine?
A bad AC compressor does affect the engine. The AC compressor is a significant part of the air conditioning system and derives its power from the engine.
The AC compressor pressurizes the AC system and keeps the refrigerant flowing for the system to work perfectly.
A malfunctioning AC compressor makes the vehicle shake when the AC is on, and in extreme cases, it can make the engine stall. AC compressor shaking is a major sign that tells you that the system at the verge of failing.
Q: How Can I Make My Car Idle Smoother?
The smooth idle of a vehicle depends on the right mixture of air and fuel. Therefore, if the air and fuel are not processed properly, you will have a rough idle.
There are various causes of rough idling. To get a smooth rough idle, you need to know the exact cause of its rough idling.
In most cases, it is due to components that control ignition and fuel. Therefore, the prudent thing is to check these components one by one.
If they are clogged, take some time to clean them. If the parts are worn out, the way to a smooth idle is by replacing them.
Final Words
Car shaking when AC is on is one dilemma that most drivers find themselves in. the above information will help you know when the problem occurs, why it happens, and how to fix it. Some people make the mistake of waiting, hoping that the issue will disappear.
Car shakes when ac is off could be caused by different factors. The prudent thing to do is to have it fixed as soon as you discover it to prevent it from worsening.
Always make sure that the AC system in your vehicle is working correctly and does not affect the car’s power.