Why is My Car Shaking When My A/C is On?

Turning on your car’s air conditioning on a hot day only to feel your whole vehicle vibrate and shake can be concerning. It can even feel as if the engine is struggling to keep everything running properly. 

This explanation isn’t that far off either, as the A/C system is reliant on the engine. Vibrations while using the A/C may seem like it’s just a problem with the air conditioner, but many times it’s actually the engine that is the source of the issue. 

How Does A/C Work?

Your car’s air conditioning works by forcing refrigerant between a liquid and a gas state. When the refrigerant switches states, it absorbs heat and humidity from the surrounding air making it cold and dry and ready to blow into the cabin. 

What Causes My Vehicle to Shake When the A/C is on?

Faulty A/C Compressor

If you’re experiencing A/C shake, one of the most common culprits is the A/C compressor. 

As stated before, the A/C system and engine are heavily interconnected. The components that run your air conditioner are powered by your vehicle’s motor. 

Your compressor is responsible for taking low-pressure gas and pressurizing it into high-pressure and high-temperature gas. 

Your A/C compressor acts as a mini engine itself, which takes a significant amount of power to keep running. So when the compressor is burned out or faulty, it puts even more load on your vehicle’s engine, which can cause it to shake. 

Allowing the compressor’s condition to worsen can lead to a faulty A/C, or if left untreated for too long, can result in excess strain and damage in the engine. 

Compressors can fail for a number of reasons, with some of the most common including failure of the internal clutch in the compressor, seizure, corrosion, or lack of lubrication. 

Worn Engine Mounts

Motor mounts are the connectors that are responsible for keeping your engine from moving excessively and keeping vibrations out of the cabin. 

With the A/C placing extra load on the engine when running, it causes more vibrations than normal. This would be unnoticeable with functional engine mounts, but faulty ones transfer more vibrations and cause the car to shake.

Worn-out motor mounts aren’t critical issues right away, but allowing them to further degrade can lead to further problems down the line, and may even pose a safety issue. You should have them replaced to avoid complications and further damage. 

Faulty Fuel Injectors

When your fuel injectors are unable to deliver the proper amount of fuel, the engine will struggle to run at its best. This can lead to shaking and vibrations when the A/C is turned on, as using the air conditioning puts more strain on an engine that might already be struggling to keep up.

Failed injectors can lead to larger issues if left untreated including misfires and failed catalytic converters, so you should bring your car to a professional for inspection and repair as soon as possible.

Animated cross section of fuel injector working
WikipedianProlific, CC BY-SA 3.0 http://creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons

Dirty Throttle Body

Your vehicle’s throttle body is responsible for regulating the proper amount of air being let into the engine as you press down on the gas pedal. Throttle bodies use a flap to control the flow of air into the motor, and as this mechanism sees carbon buildup and other debris, it can cause the throttle body to let in an improper amount of air.

This lack or excess of air causes the engine to run at a suboptimal ratio of fuel/air and can lead to reduced power and even issues such as heavy vibrations, especially under the load of an A/C at full blast.

Throttle body
Florian Lindner, CC BY 2.5 https://creativecommons.org/licenses/by/2.5, via Wikimedia Commons

A/C and Engine Services at Micro Import Service

If you’re experiencing shaking when using your air conditioning, you should bring your vehicle to a trusted professional as soon as possible to avoid problems worsening or causing damage to your engine.

If you live in Arizona, you know how essential a working air conditioning system is during the summers. Don’t let you and your passengers go without it!

The experts at Micro Import Service will ensure your vehicle is running healthy and at its best, so you can always use your A/C without worrying! Call or schedule online with us today!