Water Leaking From Car Air Conditioner (Causes & Solutions)

A vehicle’s air conditioner is an important part of the vehicle that helps maintain a warm and cool temperature in the car, depending on the weather. Now when this part of your vehicle goes bad, be sure to note that the temperature in your car will be nothing short of discomfort.

So it’s no surprise why most people are particular about the performance and state of their air conditioner, mostly during winter or summer, which is also why you’re experiencing more leaks from your vehicle’s air conditioner.

Well, I presume you must have noticed a few leaks from under your vehicle, even when the AC isn’t on. And this should be considered a brow-aching experience, especially when the leaks become too much. But you’ll never know how minor or serious the issue is until it’s been looked at professionally.

And you don’t have to be a professional to know the “why” of that situation. Because that’s what this article is here for — to fill you in on the reasons behind those leaks and how best to prevent them from occurring.

How Does A Car AC Unit Work?

The AC unit of a car works by extracting hot air from the confines of the car in exchange for fresh cool air. This procedure is called heat exchange.

This happens when heavily moisturized gases are trapped in liquid form before they’re let out via a condenser coil that works as a tailpipe.

Now the condensation formed on the coils allows water to leak if it isn’t properly repaired or maintained in time to prevent further damage.

What Are The Kinds Of Leaks Associated With A Car Air Condition?

There’re two types of car AC leaks:

1. Water leaks outside the car

It’s normal for water to leak from under your car, especially when the weather is hot and you use the AC at maximum blast. So the vehicle’s AC unit is designed to let water drain out of your car.

The unit cools the interior by extracting humidity from your vehicle; that water has no channel other than out of your car from underneath. Instead, the AC evaporator core turns the water into liquid. This liquid then goes out of the car to the pavement through the vehicle’s evaporator drain.

Now while a few drips are okay, a puddle isn’t. When the leaks become overbearing, be sure to look into them. Oftentimes it might not even be a water leak; there are other fluids that your car depends on that could also leak.

Whatever the leak is, it shouldn’t be ignored because the safety and performance of your vehicle hang on these leaks.

2. Water leaks inside the car

When your car experiences leaks on the inside, it could mean two things; (a) something’s not right, or (b) someone (maybe a toddler) spilled a cup of water, and If that isn’t the case, then your car’s AC unit is leaking water.

For instance, an aging sunroof or a badly installed windshield could let water inside the cabin. Another reason could be excessive corrosion that creates small holes in your vehicle’s body panel. What if you’ve been involved in an accident lately, a minor one at least? Those seams on your vehicle’s body could break and let in water.

The timing of these leaks could give you an idea of whether it’s related to the AC. If you observe any leaks during rainy or wet conditions, check the areas mentioned above. And if the AC is responsible, the leaks will be more frequent in hot conditions because that’s when the AC is used mostly.

Also Read: Does a Cold Air Intake Make Your Car Louder?

Symptoms of Water Leaks from Car Air Conditioner

Water Leaking From Car Air Conditioner

Most air conditioning leaks are usually close to their evaporators. That is where the evaporating coils are housed. It also cools the air in your car by taking out the heat produced by components (the engine) and occupants.

Most people believe that a leak is caused due to the fluctuation of their compressor, but that isn’t the truth. A leaking unit gives clear symptoms and signs that are hard to miss.

Even if the leaks are evaporator leaks, the refrigerant level usually drops below 75% before it gets recycled into your vehicle’s “high” side with every compressor cycle, usually every 30 seconds.

The compressor won’t be activated if this process doesn’t occur. Nevertheless, it’s okay for the levels to decrease that low.

Below are the likely but basic signs of a leak:

  1. An unpleasant smell that smells like Freon gas or Sulfur, usually because refrigerant is leaking out, polluting your car’s cabin. A lot of people are quick to recognize the smell as Freon or refrigerants.
  2. Seen water in the passenger’s seat area or on both sides of your windshield visor on the window pane in front.
  3. Seen water on some areas of the dashboard and around the carpeting. Because the elevator system is sealed, the water tends to leak inside the car.
  4. When starting your engine and using the AC, condensed water is found on the windshield. This happens mostly when the level of humidity is high outside your car or when driving through long traffic with the AC unit on.

Causes of Water Leaking From Car Air Conditioner

There’re several reasons responsible for car AC leaks. But we will be considering the five major reasons behind these leaks.

1. Blockage in the Condensate Drain Pipe.

There’s usually a leak inside the car to know if the condensate drain pipe is blocked. So if you find out that the floor of your vehicle is wet whenever you activate the AC, immediately check the condensate drain if it’s blocked. Because when it is blocked, it drains it inside the vehicle rather than drains water out of the car.


Unblocking the condensate drain isn’t so much of a task, provided you’re conversant with your vehicle’s engine and parts. You’d first need to locate the hose of the (CD) condensate drain, mostly found at the end of your engine around the passenger area.

After finding it, bend or squeeze the hose to let out any debris inside it. You could also carefully use a screwdriver to clean the hose of any leftovers. Remember, do this carefully so as not to damage your ventilation system. And if you aren’t confident in getting it done yourself, that’s not a problem; kindly seek the help of a professional for air conditioning to get it done.

2. The Condensate Drain is Not Properly Attached to the Ventilation System

When the condensate drain isn’t properly connected to the ventilation unit, there’s bound to be water leaks from the air conditioner into your car. This inappropriate attachment hinders the drain from doing its primary job, which is to drain out the water from the vehicle.


Doing this shouldn’t be a problem if you’re familiar with the parts of your vehicle and provided you don’t mind a little dirt because this is kind of messy.

You’d first need to find the condensate drain below the evaporator; that is, in the compartment of the passengers’ seats or at the base of your car’s ventilation system. After locating, properly connect the condensate drain and see if it flows outside your car.

And if you aren’t sure, do not hesitate to seek the assistance of a professional repairman.

3. Low Refrigerant Level

A certain level of refrigerant is required of a car’s AC system to help it circulate and distribute cool air throughout the car’s cabin efficiently. When this refrigerant level is below the required range, the pressure on the AC system is decreased. Unfortunately, this makes the evaporator coil freeze and ice up, causing the CD pan to flow over and leak.


One way to know that your vehicle’s refrigerant is low is that it disseminates warm air in place of cool air. Servicing your vehicle’s AC system is one way to check and refill the refrigerant levels as required. And this can only be done by a professional.

4. Dirty or Blocked Air Filters

Over the cause of time, your AC air filter gets filled with dirt from moisture and dust. That is why it’s necessary to have the AC serviced and checked yearly for the air filter to maintain cleanliness. In addition, this dirt accumulation could block the filter, freezing up your vehicle’s AC evaporator coil, which could result in excess water flow from the CD.


Keeping your car’s air filter clean is very necessary, & this can be achieved with the expertise of a professional. Have your car serviced and checked at least yearly or as instructed in the owner’s manual or advised by the manufacturer. Constant servicing of the AC prevents any form of blockage.

5. Broken Condensate Drain Pan

The CD pan is liable to break and rust due to wear and tear and aging. Accidents could also cause a broken CD pan; as a result of this break, water can leak from the AC.


Based on the damage, a broken CD pan should be changed. It should be checked by a professional car repairer and changed when due.

Also Read: How to Clean Mass Air Flow Sensor With Alcohol (Expert Guide)

What Causes Car AC Freon to Leak?

The cause of a leaking Freon is not exactly ascertained, but when the fan of an air compressor fails, a small number of metals are released throughout the vehicle’s AC system, which could cause damage to other AC components. Consequently, creating holes for refrigerants to leak out.

Also, the AC system is found under your vehicle, which subjects it to harm from debris and heat. They’re the prominent causes for a vehicle’s Freon to leak.

A leaky gasket, damaged seal, or various malfunctioning parts of the air conditioner system can make refrigerant leak. The reason is that Freon runs through your car’s cooling system, and any leaking component could be responsible.

How Much Does It Cost To Fix A Leaking Car Air Conditioner?

Water Leaking From Car Air Conditioner

An AC unit of a car that’s faulty is a vital problem that requires the help of engine parts. You might have wondered how much it’s worth to get your AC fixed should anything go bad. Well, that depends on what happens to the air conditioner.

Installing New Air Conditioner

In a situation whereby the whole unit goes bad, you’d need to change your vehicle’s air conditioner. And the price for installing a new AC system is from $1,500 – $4,000.

Having said that, those are subject to the year, model, and brand of your car. Either way, the price of getting and installing a new car air conditioner system is high.

Leaking Cost

You’d first need to determine the root behind any puddle growing underneath your car with the help of a mechanic.

Based on the damage, the cost might range from $150 – $800

System Evaluation Cost

For this, the cost is around $100 & $300 for a repairman to check the system and how it operates. This check includes the hoses. Next, connectors and belts, and the mechanic will conclude with a refill of big fresh refrigerants.

Also Read: How Much Does Coolant Leak Repair Cost?

Frequently Asked Questions

Is it normal for water to leak from the car when AC is on?

Provided its water and you’ve been utilizing the interior heater or AC, it’s possibly just the condensation process. The evaporator core releases water from below the passenger seat when using the AC.

Do car AC leak sealers work?

Certain AC sealers work efficiently, especially for small holes, but they are not recommended because they’re not proven to stop leaks on shaft seals or O-rings, which are more common compared to pinhole leaks.

Why would water be leaking from under the dashboard on the passenger side of a car?

While the AC evaporator takes heat out of the car’s cabin, so does its humidity. So, the condensation usually barely leaks out of the vehicle while driving. And should you have observed such leaks from your undercarriage on a sunny day, it is usually condensation only.

When should I stop AC leak?

The moment you’re certain there’s a leak in your system, you can seal up the leak with an air conditioner to stop the leak or change the leaking components, which is far better.

How long does it take to fix an AC leak?

It takes about 2 to 4 hours, depending on how the system is. So a preferable situation is one whereby the area of damage simply requires you just tightening it to get it fixed.

How much stop leak should I use?

½ bottle is used for 4-cylinder engines. A bottle is sufficient to treat 4 gallons. While for a larger system, one bottle for every three gallons. Smaller engines use about 3-4 fluid ounces for each gallon of fluid.

How do I know if my car AC is leaking refrigerant?

You’ll know for refrigerant leaks that are visible. Also, the Freon level is visible enough to tell you that something isn’t right. The moment you sense a leak, you’ll, and it feels like a light greasy substance that should tell you it’s Freon. Another thing is the leak usually appears beneath the hood, close to the compressor under your car, or in the cabin.

Why is my car leaking water but not overheating?

You’re probably experiencing a leak in your radiator cap, or coolants are leaking externally or internally. Unfortunately, the longer this takes, the more damages occur, making the repair cost higher. So it’s best to learn how to detect when there’s an antifreeze leak & what to do when you do.

Final Thoughts

Having an AC system that works is one of the best experiences for your ride in both summer & winter because this system helps you control the temperature of your car’s interior as you please. However, this AC system has shortcomings, like a situation whereby you have to deal with excessive leaks from under your car. How about leaks inside your car? Trust me, that’s one “not so good” experience.

Nonetheless, at this point in this article, it is believed you know the reasons behind those leaks and how best to prevent them. Ensure to always have a mechanic check your vehicle anytime you notice something strange or out of place. Water Leaking From Car Air Conditioner

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