Why is water vapor coming out of my AC vents in my car?

Author: Diana Quigley  |  Last update: Wednesday, September 3, 2025

“The odorless steam coming from the vent is possibly excess water accumulating in the heater box, which may indicate the drain hole is restricted and needing cleaned.” Dave Carney, president of Hillside Auto Repair in Torrance, said the problem usually occurs in older cars.

Why is there water vapor coming out of my car AC?

Sometimes it can be caused by water accumulating in the vent system after it condenses. That water can wind up at the bottom of a vent, and when you turn on the blower motor, it can cause what looks like steam or vapor to come out of the vents.

Why is there vapor coming out of my AC vents?

The cause of sweating vents is simple. Air that's humid enough finds a surface cold enough. When vents start beading up with water--or worse, dripping--either the humidity is too high or the vent is too cold. It's not hard to figure out which of those two is the culprit. Just find the dew point of your indoor air.

Why is moisture coming out of my car AC vents?

  • Clogged Drain Line : The AC system has a drain line that allows condensation to escape from the evaporator.
  • Damaged or Disconnected Drain Hose
  • Faulty Evaporator Core
  • Blocked Air Intake
  • Weather Stripping Issues
  • Condensation Build-Up

Why is there liquid coming out of my car AC?

This is the result of condensation from the cooling mechanisms that are hard at work, particularly if it's a scorcher of a day. Take a close look at the puddle to make sure it's not a sign of something more serious; condensation should be clear and non-odorous.

Why is white smoke coming out of the AC vents in my car?

Why is water coming through my AC vent?

A Broken Condensate Pump

The water from your AC collects in this pump. From there, it is pumped outside of the home. If that pump breaks, the water won't drain from the house properly. As a result, it may drip from the air vent.

How do I get rid of condensation in my AC vents?

What can I do about ductwork sweating?
  1. Reduce the humidity level around your air ducts. Keep ducts spaced apart so air can flow between them. ...
  2. Unblock any ducts that are restricting air flow and have them cleaned regularly. ...
  3. Keep your air filters clean and change them regularly. ...
  4. Repair leaking ducts.

Why is there steam coming out of my AC?

The purpose of the drain hole in air conditioners is to allow condensation to escape. However, over time, dust and debris can build up causing a blockage. This leads to backed-up condensation in the air conditioner which then gets released as a mist or fog from the AC vents.

Why is my AC blowing moisture?

The AC Condenser Coils Need to Be Cleaned

Over time, these coils can become clogged with dirt, dust, debris, plant matter, and more. This build-up of contaminants can prevent the coils from doing their job properly, resulting in humid air being blown into your home instead of cool and dry air.

Why is there fog like mist coming from my AC vents?

Air Conditioner Drain Hole is Clogged

This component helps drain the water outside, away from your cooling unit. Unfortunately, it can get clogged as time passes, and this can cause the water to back up into your air conditioner. A white fog will then be released from the vents if this happens.

Is it normal for steam to come out of your car?

For example, white steam will sometimes rise from your car exhaust on a cool day as it heats up. This is no cause for concern, however, there are many other reasons your engine could be steaming. Some of them include: A leak in your cooling system.

Can car AC vents get clogged?

Over time, air vents can become clogged with dust, debris, and even mould, hindering airflow and diminishing the quality of the air you breathe creating bad odours.

What is the water vapor in my air conditioner?

If the moisture higher and condensed it is called as mist or dew or rain etc. As the A.C machines cools the air, the moisture is also cooled and moisture is in the form of steam or vapor and it condenses and changes to water and the A.C machines drips it away. It's not harmful, it's normal.

What are the symptoms of a bad AC drier?

Below are some signs of a bad car A/C receiver drier.
  • You Detect a Moldy Scent. ...
  • Rattling Sounds. ...
  • Refrigerant Leakage. ...
  • The Filter Drier May be Clogged. ...
  • What Should Be Done to Remedy the Problem?

Is water leaking from car AC normal?

Despite the way it may look, your car leaking water from the AC is usually not serious. Whenever you activate the air conditioning, it creates a bit of condensation, which can present as a small puddle of water. If you see small puddles like these near the back of the engine compartment, that's probably the cause.

Why is vapor coming out of my AC vents?

Don't worry—it usually doesn't mean there's something wrong with your air conditioner. The mist is just condensed water vapor that forms when cold, dry air comes into contact with humid, warm air (we'll explain this in more detail later on). Usually, the mist will go away on its own after a minute or two.

Why is mist coming from car AC vents?

“The odorless steam coming from the vent is possibly excess water accumulating in the heater box, which may indicate the drain hole is restricted and needing cleaned.” Dave Carney, president of Hillside Auto Repair in Torrance, said the problem usually occurs in older cars.

Why does AC release vapor?

If the air temperature near the appliance is below the dew point, this causes water vapor to form in the air and condense into water droplets, thus causing the fog or smoke. A dirty air filter or low fan speed may aggravate the condition.

What does water dripping from an AC vent mean?

Most commonly, water dripping from your AC vent results from leaky air vents. If the air is escaping around the grates of your AC vents, it will cause a buildup of condensation that will inevitably start dripping all over the place.

Is condensation from AC bad?

Without prompt attention, excess condensation could overwhelm your air conditioner's drainage system, causing damage within your home. This damage can range from high humidity levels that lead to mold and mildew proliferation and spots, to structural damage from drainage water that accumulates and puddles.

How to get water out of air ducts?

How to Dry Out Wet Ductwork
  1. Turn off your humidifiers, they add moisture to the air and can lead to your ducts getting wet.
  2. In rooms with high humidity such as an attic, use a dehumidifier.
  3. Find gaps in your air ducts and seal them. Do this using material such as tape or plastic wrap.

Why is my car AC vent leaking water?

Blockage in the Condensate Drain Pipe

If you find your car's floor getting wet with water whenever you turn your car's air conditioner on, then it's time to check your condensate drain. A blocked condensate drain keeps the water from draining outside your vehicle, causing the water to overflow inside the car instead.

What does it mean when your AC spits out water?

Usually if you notice that your window AC unit has started spitting out water inside, it means the unit is tilting too far inward or that the sling fan has been damaged. Try tilting the window unit outward to see if this resolves the problem.

How do you fix condensation on AC vents?

So, How do You Stop Condensation on Ductwork?
  1. 1 . Put Insulation Around Your Ductwork. If your ductwork lacks an insulation , you better insulate it before summer starts and you start experiencing condensation issues. ...
  2. 2 . Check if The Insulation is Damaged and Repair it. ...
  3. 3 . Ensure your HVAC Air Filters are Clean.

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