Why Is My Car AC Blowing Smoke? How to Fix

There’s nothing mystical if your AC blows out smoke. It simply indicates that something is probably wrong within the system. Of course, you may wonder, “Why is my car AC blowing smoke?” This is a malfunction, and it can be rectified.

So, kindly take a moment to study every bit of this article to find out the cause of car ac blowing smoke and how to fix it as soon as possible.

why is my car ac blowing smoke

What Does It Mean When Your AC Blows Smoke?

If your car’s air conditioning system blows smoke when you turn on the component, it simply means there’s a contact between warm air from the AC and your car’s interior, respectively. At the same time, the contact has triggered a condensation responsible for the AC smoking.

Usually, moisture or water vapor forms when your car’s AC temperature is below the dew point. Once this occurs, the vapor or moisture condenses in the air and automatically becomes water droplets that create fog or smoke. However, the smoke is usually odorless and not harmful.

On the other hand, a car air conditioner blowing white mist may also indicate that excessive water has been stored within the components heater box. This is usually caused by a blocked drain hole that requires thorough cleaning.

AC blowing smoke in a car may be a minor or major issue, depending on the actual cause. If the contact between the warm and cold air is the issue, it is relatively a light issue.

However, understanding what the white smoke from AC vent means and the cause of the occurrence will help you figure out a remedy as soon as possible.

Why Is My Car AC Blowing Smoke?

Sometimes, malfunctions are not unnatural. However, allowing some faults to linger without a quick fix can be detrimental in the long run. For example, the air conditioning system is a delicate component, which can become faulty when you least expect.

The phenomenon of your car’s AC blowing smoke, which can appear as the fog through the vents, is a sign of malfunction. There are several reasons why this may occur. One common parent issue could be a failing AC compressor, which is critical among vehicle components for proper AC function.

When troubleshooting, if you notice white smoke, it could indicate the presence of refrigerant leaks making contact with hot parts of the engine, causing smoke to run through the AC vents. Malfunctions in the AC system might also produce smoke due to other faults in some components along the cooling system. Let’s go through some of the reasons for smoke coming through car vents include the following.

Clogged drain hole

Most modern air conditioning systems are designed to collect the condensation that results from the AC’s operation and use the same to cool the component. However, older AC systems were built with a drain hole where the water from the condensation is allowed to escape.

Therefore, when the drain hole becomes blocked due to usage over time, the water from the condensation will be stored. Meanwhile, the heat from the AC will eventually act on the accumulated water and turn it into steam, which will be released into the car’s interior via the car air vents.

High humidity

The air conditioning system is built to react to humidity. In this case, if the humidity level around the AC system is less than the normal humidity level, it will produce a fog which is further released via the AC vents.

Heated core

This is common for people who usually engage the HVAC system’s heater. When the heat affects the core, it will cause a leak in the component. Meanwhile, this will further cause a release of smoke via the AC vents into the car.

Defective AC compressor clutch

This is a culprit to the issue for ac compressor smoking. Sometimes, the AC vents may release smoke coming from another faulty component. In this case, a defective compressor clutch that is affected by overheating may release smoke, which the AC will most likely suck into the car’s interior.

Low freon level

Low refrigerant levels could also be another reason your car smokes when AC is on. The oil is responsible for cooling the air conditioning system from high temperatures. Therefore, a shortage in the fluid level may trigger overheating and cause the release of smoke.

Again, the AC may not be able to avoid the smoke. It may also suck up the smoke and blow it into the car’s interior through the vents.

How to Fix Blowing Smoke of Car

Once you identify the actual cause of the smoke coming from your car’s air conditioner vents, fixing the issue is just about a few steps away. However, taking instant action is necessary if you must get things done. Therefore, if you notice your air conditioner blowing white mistor smoke, the following recommended solutions can help you tackle the situation.

Unclog the blocked drain hole

If the smoke coming out of ac vent in car is caused by the steam formed in the air conditioner due to a blocked drain hole, unblocking the component will resolve the issue immediately.

However, this is a task for a professional HVAC system technician. Nevertheless, if you understand the system, you can check it out.

Top off/change the oil

After inspecting the air conditioning system and other components, if you discover a shortage in the oil, kindly top off the fluid level or change the oil completely. Again, this can be handled by a DIYer. So, if you’re sure of doing this, why not?

Refill refrigerant

Refilling the refrigerant can also help to rectify the smoke from an air conditioner. In this case, if you find out that the air conditioning system’s coolant level is low due to the leak in the heated core, ensure to fix the component and refill the refrigerant.

Replace the defective AC compressor

The AC compressor is a major component in the system. Therefore, if every other part is intact and a problem exists in the compressor, the parts will still malfunction. So, ensure to replace the faulty compressor if this is the issue.

bad compressor

Meanwhile, sometimes you may be tempted to repair a faulty compressor clutch once you notice this problem. However, the compressor may develop another fault. So, replacing the AC compressor would be best.

Fix electrical faults

Lastly, if an electrical fault is a reason for the smoke coming out of car vents, fixing the fault will help to remedy the situation. Usually, electrical faults, especially burning wires, come with a burned smell, apart from the smoke. So, ensure to look out for this symptom.

However, fixing electrical faults is also a job for professional auto technicians, except you’re a sophisticated DIYer that can handle the repair.


This article has exposed some of the reasons you may suddenly turn on your car’s air conditioning system and the vent blast out smoke. Sometimes, it may be a result of a faulty component.

Other times, it could be a minor issue that you can personally rectify. However, leaving some minor faults for a long time may result in damage in the long run.

So, if you know someone who’s facing this kind of situation and is asking, “Why is my car AC blowing smoke?” Recommend this article as a prescription. The information above will be relevant to them.


Mr. Shafiqule Islam is a graduated Mechanical Engineer and has more than 15 years experience of repairing and maintenance of different brand vehicles like Toyota, Mitsubishi, Ford, Mercedes, BMW etc. He is also giving training to Mechanics. He has started writing to share his practical knowledge to Vehicle Owners, Drivers and Mechanics to keep their cars at best fit.

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