Is your car leaking water underneath passenger side after a car wash or driving under heavy rain? This can result from a blocked drain tube, a leaked door seal, or a damaged gasket.
However, if your car leaks water under the passenger side during summer or while traveling in a humid area, it can be caused by running the air conditioning system.
Water leaking isn’t concerning except for a little bit of irritation. However, you can repair the door seal, close the door properly, and repair the AC to avoid excessive water leaking under the passenger side.
Article Summary
Why is My Car Leaking Water Underneath Passenger Side?
AC drains, sunroof drains, and heater cores are common sources of normal water drip under the car’s passenger side.
Other potential reasons are a faulty seal, defective door seal, or coolant leak. However, you must make sure the liquid leaking under the passenger side is water.
The reason is that coolant or other engine fluid can also leak from the same root, which is a serious concern and needs different repairs.
To determine it, check the liquid using your fingertip to see if it’s oily and colored orange or green and if it’s more concerning coolant. But if the liquid is only clean water, below are the potential reasons and solutions:
1. Blocked Drain Tube
If you notice water leaking underneath the passenger side and wetting the carpet, the water may come from the clogged drain tube.
The drain tube runs under the passenger side and is placed behind the carpet where the passenger rests their left foot. It also runs through the floorboard to the outside of the car to drain water below the car.
It can be blocked due to debris and prevent water discharge properly, so you can notice water leaking under the passenger side. It can also get cracked and prevent draining water.
The drain tube should be visible after pulling the carpet out from the slanted floor. To repair the damaged drain tube, wiggle the tube top of the nozzle. Then, use a can of aerosol duster to blow the tube out and clean the nozzle using a Q-tip.
2. Faulty Seal and Gasket
If you notice water leaking into the car’s passenger side, particularly after replacing the engine, a faulty seal can be the reason.
There is a seal between the car’s body and engine that prevents water from entering the cabin. This seal can leak water inside from the passenger side if it becomes weak or is not installed properly.
The improperly sealed gasket can’t prevent moisture from seeping through, which can leak water. The water can also enter the cabin through the passenger side due to holes or cracks in the firewall.
To fix this problem, ensure all the gaskets and seals are installed properly and in good condition after replacing the engine.
3. Air Conditioner
If you are driving a car in a humid area and using the car’s air conditioning system, you may notice the vehicle leaking water underneath the passenger side.
If so, don’t panic; it’s only the meltwater. When running the car’s AC in a humid area, ice can build up on the pipe that carries AC fluid between the heat exchanger and the compressor.
After turning off the vehicle, the ice may melt slowly and leak under the passenger side. The water may also condense in the AC’s heat exchanger, which is placed inside the car’s dashboard and may drain away under the car through the passenger side.
There is nothing to worry about if water leaks out of the AC during the summer season. In extremely humid climates, your car can leak a steady drip or even a stream of water underneath the passenger side. But if you are worried about it, seek professional help.
4. Defective Door Seal
A faulty door seal can also cause your car to leak water underneath the passenger side. If you experience this problem, particularly while driving on wet roads, a defective door seal is an obvious reason.
To determine this problem, carefully check where the car’s door closes against the car’s body.
A thick rubber gasket runs around the opening, preventing rainwater or road splash from entering the car.
It also keeps the car inside dry during the car wash. If the seal gets leaked, water may enter the cabin and drain under the passenger side. If so, you must replace the leaked door seal to fix the problem.
The sunroof can also get a leak that runs down the pillar. Rarely do some modern cars leak water underneath the passenger side due to the floor plan’s faulty grommet or leakage around the mounting belt. In this case, you must bring the car to an auto repair shop.
5. Header Tank
The exhaust may push out a little water due to the fuel’s combustion. So, you can notice a wet patch underneath the tailpipe, which is pretty normal.
However, an overheated motor can cause water to steam in the cooling system and cause small puddles.
If so, you shouldn’t ignore it. You may also notice water under the passenger side of water in the system overflow. Water can also overflow from the header tank.
When the car reaches the operating temperature, the water will overflow through a hose to the passenger side.
6. Crack Windshield Seal
Water may also leak inside the vehicle on the passenger side and run down on the carpet due to cracked water. It’s particularly true if the car leaks water after a car wash or driving under heavy rain.
The windshield seal can crack down due to accident or rough use. However, you can experience the same consequences due to door seals, inaccurately closing the door or AC blockage. So, it needs deep inspection.
Should You Be Worried If a Car Leaks Water Underneath the Passenger Side?
No, water leaking is not a major concern. Since it can occur due to AC, damaged rubber seal, or exhaust condensation, it won’t impact your car’s performance.
However, whether you should be concerned or not depends on the cause of the water leaking under the passenger side. If your car leaks water due to running the AC during summer or in a humid area, don’t worry.
It’s also okay to notice some water under the passenger side after a car wash or driving under heavy rain. Simply check the door seal and gasket and replace them if required.
However, if the leaking water results from clogged drain water or a cracked windshield, driving can be risky and irritating.
In this case, bring the car to the nearest auto repair shop and fix the issue. Otherwise, excess water under the passenger side can cause corrosion or mold buildup.
How To Fix Car Leaking Water Underneath Passenger Side
You have a car that is leaking water underneath the passenger side. Depending on what caused the leak, multiple possible repair choices are available. Here is how to examine and possibly repair the problem.
1. Condensation from the AC System
- Clear and odorless water? Yep, that’s AC condensation and completely normal.
- Check the AC drain tube for blockages of dirt or other debris, which can clog the tube and cause water to accumulate inside the cabin.
Fix: Find the drain line underneath the car (usually on the passenger side firewall) and flush it out with compressed air or a stiff wire.
2. Blocked Sunroof Drains
- Sunroofs have pipes that drain down the windshield. If these get clogged, water can leak into the cabin, collecting on the driver’s side.
Fix: Check that water can drain through the outlets beside each corner of the sunroof. Use a hooked wire or compressed air to remove any blockages.
3. Damaged Weather Seals
- Survey the door and window seals, especially the rubber gaskets, for weathering or damage that could lead water into the vehicle.
Fix: Buy weather seals and replace them. The rubber is both elastic and adhesive. You can buy seal replacements at an auto parts store and simply install them, or have them installed at an auto parts store.
4. Leaking Heater Core
- If any drops have a sweet odor or are dark green, orange, or pink, they’re probably from a leaking heater core.
Fix: Replacing the heater core is not easy because the original part is typically sealed inside the car and often requires professional service to remove the dashboard to reach it.
5. Clogged Cabin Air Filter Housing
- If your cabin air filter is clogged or not installed properly, it can cause water to back up and drip onto the passenger side of your vehicle.
Fix: Open the glove box and remove the filter. If it is dirty or clogged, replace it. Inspect the housing. If it’s full of water, drain it or replace it with a new one.
Additional Tips:
- Once the problem is fixed, dry the area thoroughly to prevent mould growth inside the car.
- Put a pack of silica gel or charcoal in the car to reduce humidity.
If you do this and the problem persists, please have a mechanic do a detailed inspection.
Fixing Cost of Water Leakage Under Passenger Side
In most cases, you won’t have to break the bank to fix the water leak problem. But if you need to replace the AC evaporator to fix the water leakage, it can cost about $1000.
The other expensive repairs are repairing the car’s window and door and replacing the heater core, which can cost $500 and $1200, respectively.
But in most cases, you may only need to repair the rubber seal, which will cost less than a hundred dollars.
FAQs on Car Leaking Water Underneath Passenger Side
Is Water Leaking from the Car AC Normal?
It’s normal if your AC leaks water outside the vehicle. But if the water leaks inside the vehicle after turning on the AC and it’s too much water, don’t take it lightly. Instead, consult with an expert mechanic.
Why is My Car Leaking Water Under It When Parked?
You may notice water leaking under it after parking. It can result from the condensation of your car’s AC system. If your car’s air conditioning system produces condensation, the water will start dripping and forming a puddle that you’ll notice near the engine housing.
Why is the Car Leak Water from the Front?
Your car may leak water from the front due to an overheated motor or excessive water in the cooling system. A faulty radiator cap or loose hose can also cause water to leak from the front of a vehicle.
What If the Water Leak Continues Even When the AC is Off?
For instance, if a leaking AC is accompanied by an ever-present drip even when the air conditioner is not running, then the problem is likely not condensation but a leaking heater core or rainwater intrusion through damaged weather seals and blocked sunroof drains.
What Should I Do If the Water Leakage Persists?
If there are persistent water leaks, it is best to consult a mechanic. You should try to fix the problem causing that line, e.g., a leaking AC drain or a leaking heater, to avoid potential damage to your car’s mechanics, the interior, and various electronics.
Final Words
If your car is leaking water underneath the passenger side, don’t panic. Instead, troubleshoot the underlying source that is causing water leakage.
Above all, ensure your car leaks water as it isn’t concerning. But if your car leaks oily, green coolant or engine fluid, consult a professional mechanic immediately. This can result from serious concerns like tank leakage, insufficient fluid, or engine damage.
