Why Is Smoke Coming Out Of Ac Vent In Car?

Have you ever seen steam or steam coming from the air vents of your car during the air conditioning operation? You could have been shocked first, perhaps even wondering whether the automobile was on fire. Astonishing numbers of drivers have reported that steam comes from the air, so it is wise to learn about it. 

Learn the reasons and solutions for smoke coming out of ac vent in car in this easy article. The problem is not that hard as you might have thought of. 

Why Smoke Coming Out Of Ac Vent In Car?

So it is vital not only to recognize when the smoldering car ac vents are a signal of concern, aside from those very cold days. Here’s a list of types of smoke or vapor that you can witness from the ac vents.

1. Excess Water In The Heater Box

Excess water in the box is presumably the smell-less, white steam, or smoke from your air conditioner. It is usually a symptom of a small drain hole that gets clogged and requires cleaning. When the cold air impacts it, the steam gathered during the condensation process could have been released, making it smoke.

How To Drain Water From Heater Box?

If this is the case, you should check the HVAC box drain pipe location. Once found out that the smoke is because of the accumulated water in the drain hole, the only thing is to do is to pump the water out by unclogging the pipe or by removing then bent or a kink in the pipe. 

2. Cold Dry Or Humid Air In The Atmosphere

If the cold air strikes the warm air, it could cause white smoke or fog. The water vapor and moisture form when the temperature of the unit is below its dew point, then, droplets condense in the air, they form smog or fog. It can make the smoke worse if your indoor moisture is higher than usual.

The situation might also be made worse by low fan speed and blocked air filters owing to the build-up of dirt.

Solution In Case Of Humid/Cold Air

In case of the environmental factors, you cannot do much about it. Always keep the air filters clean. Run a high-speed A/C fan to cool your indoor air much more quickly. Regular inspection schedule for A/C. You can also mix some hot air by adjusting the temperature from the Ac pannel. 

3. Electrical Burning Smell

This is a big issue and needs to be addressed immediately if it is the cause of smoke coming out of ac vent in car. If this happens, it is preferable not to drive the car. The good news is that in new vehicles, the electricity trouble of this type is rare. Please note that the section of the electrical system could be shortened by having a musty smell and water leaks into the automobile.

Cars have several computers, and those near the ground can become wet and short.

How To Deal With The Electrical Problems?

The source of the matter can be a rusted loose battery cable. If your car doesn’t start, check the connections. If it is the culprit of your trouble is a blown fuse, it is a quick and straightforward fix. The battery could also be the source or it could be a damaged or malfunctioning alternator.

You may bet on alternator problems if your automobile starts to lose electrical function, such as dim heights.

4. Steam From Under The Hood

There is no need to worry if you observe the steam-like stream flowing from under the hood. Water vapor from the cooling system is entirely natural and caused by the development of condensation from hot parts when water hits them. But if there is a leak in the cooling system, then it needs to be addressed. 

Solutions For Cooling System

When the steam stops, open the cap very gently, as the coolant may pour out of the damaged tubing. Before opening the hood, please confirm that there are no boiling coolant jets to disfigure you. At this time, the engine is too hot, so be prepared to wait at least an hour before touching anything to prevent burning. You should get it checked immediately in case of a leak. 

5. Heater Core Leak

That’s not great news if the cause of smoke coming out of ac vent in car is the core of the heater. It is hidden in the dash and the engine flows the hot coolant into it. It might begin to disintegrate with age or neglect and enter the ventilation system. You should minimize your use of the car and have it fixed as quickly as possible if this happens.

How To Fix Heater Core Leaks

Replacing a faulty heater core is a complex procedure, but it might cost several hundreds of dollars if the mechanic does the job. If you cannot afford a new substitute and need a temporary fix, you can work to replace it. You can also bypass the heater core as a temporary solution. 

Can I Drive With Smoking Ac Vents?

The answer would be a big NO if the cause of the smoke is a heater core leak or electrical smoke. They have the potential to kill you or they can cause a big health hazard if you continue to drive your car. You can potentially burn your car down to ashes if you do so. 

How Much It Cost To Fix Ac Vent Smoke?

That depends upon the source of the smoke. If the smoke or fog is coming out due to environmental factors, then it can be fixed for free. If there is a clogged drain, then also it is a free job. But if the cause is cooling system related or if there is an electrical issue, then it can cost you between 600$ to 1000$.


First of all, do not worry if see smoke coming out of ac vent in car. But you should also not neglect it and address it as soon as possible. Things like electrical and cooling system-related problems have the potential to cause some major harm. If you still have any doubts, then comment down below. 

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