Car Air Conditioner Blowing White Mist [Causes & Fix]

An air conditioner helps to cool your car and offers you a comfortable driving environment. But when it starts blowing white mist, it can make you feel uncomfortable, especially during the hot summer.

If you’re experiencing a car air conditioner blowing white mist, you’re not alone. Because this is a problem that many drivers have encountered, and it’s usually not a cause for concern.

However, we will help you identify some reasons for this issue and provide solutions for getting your air conditioner back to its normal function.

Car Air Conditioner Blowing White Mist

Why is Car AC Blowing White Mist?

1. Humid Air in the Atmosphere

As a result of warm and cold air, white smoke or fog may form. When the temperature of the unit falls below its dew point, it produces moisture and water vapor.

These vapors condense in the air and produce smog or fog. The smoke might worsen if the indoor moisture level is higher than usual.

Also, a low fan speed and clogged air filters as a result of dirt accumulation could make things worse.

The Solution to Humid/Cold Air

  • Ensure to always keep air filters clean. Since you are unable to influence environmental factors. 
  • Run a high-speed A/C fan to rapidly cool the air inside.
  • Carry out the A/C system inspection cycle schedule for your car. 
  • Adjust the temperature on the AC panel to mix some hot air 

2. Electrical Issues

This is another reason white mist could be coming from the car’s air vent and it is a serious problem that needs to be addressed right away.

It could be a result of a loose battery cable that has rusted. Therefore, it is best to avoid operating the vehicle if this occurs. 

How to Fix Electrical Issues 

Examine the connections. If a blown fuse is the cause of your issue, then you need not worry so much because it is an easy and fast fix.

The source might also be the battery or an alternator that is broken or not working properly. You can replace it or take it to a professional mechanic to get it fixed.

3. Excess Water in the Heater Box

The extra water in the box is probably your air conditioner’s odorless, white steam or smoke. Typically, it is a sign of a tiny drain hole that needs to be cleaned after becoming clogged. The condensation process built up enough steam to smoke when exposed to the cold air.

How to Drain the Water from the Heater Box 

When it is determined that the water buildup in the drain hole is what is causing the smoke, you then have to locate the HVAC box drain pipe. Remove the bend in the tube or clean the line to pump the water out.

4. Plugged Air Conditioning Drain Vent

A plugged AC drain vent can cause liquid water condensed by the evaporator to be blown by the fan into the cabin.

And this excess moisture can cause a misty odor from your A/C system and if the water level overflows the catch tray. This can get your carpets wet and also cause the white mist to blow from your AC. 

5. Steam From Under The Hood

If you see steam coming from under the hood, it could likely be the reason your car’s air conditioner is blowing white mist.

The cooling system’s water vapor is entirely natural and is brought on by hot parts developing condensation when water is poured on them. Therefore, if be the case, you don’t need to panic.

Solution for Steam Under the Hood

Open the cap very gently after the steam stops, as the coolant may leak out of the broken tubing. Check to make sure there aren’t any boiling coolant jets before opening the hood.

Be ready to wait at least an hour before touching anything because the engine is currently too hot and could burn you. If there is a leak, you need to get it checked right away and get it fixed.

6. Heater Core Leak

A leak in the heater core can lead to your car air conditioner blowing white mist. The hot coolant from the engine runs into this heater core, which is then concealed in the dashboard.

With time or negligence, it might start to deteriorate and find its way into the ventilation system. 

How To Fix Heater Core Leaks

A damaged radiator core must be replaced, which is a hard process that could cost hundreds of dollars to complete.

You can labor to replace it if you need a temporary fix but cannot afford a new replacement. The heating core can also be temporarily bypassed.


Can I Travel With Smoking AC Vents? 

If a heater core leak or electrical smoke is the source of the smoke, the response is a resounding NO. It could pose a serious health risk if you keep driving your vehicle. If you do that, your vehicle might end up being destroyed.

Is an odorless White Smoke Safe?

If the vapor is odorless, you are completely safe because it is most likely due to humidity or condensation. However, if it stinks like burnt wire due to mechanical corrosion or something, you could be in major danger.

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White mist blowing from your car’s air conditioner could indicate several problems and condensation in the system is the most frequent cause. This situation is harmless and can typically go away after a few minutes of use. 

However, if the mist continues, it might be a sign of a compressor problem, an air filtration blockage, or a refrigerant leak. In some cases, it might also be an indication of a more severe issue with the cooling system or engine. 

Therefore, it’s crucial to have the problem diagnosed by a qualified mechanic who can correctly determine the problem and fix it.

Regular upkeep, such as replacing the air filter and checking the refrigerant level, can help prevent this problem from developing in the first place.