AC Water Leaks Inside Car – How to Fix
October 9, 2009 2:52 pm Air Conditioning, Consumer, DIY, Tech/Mechanic
The Robinair AC Machine is one of the most popular units for car air conditioning service.
©DenLorsTools.com Summary: In this auto repair article we discuss the reasons why a car’s air conditioning system may leak water inside the vehicle. Sometimes the fix is simple and other times the repair can be much more labor intensive. As an automotive technician that’s worked over 25 years in Florida, I’ve dealt with this problem many times on different models. If leaks aren’t fixed quickly, the carpet and padding underneath can become a breeding ground for mildew and harmful bacteria. People with certain allergies can be affected the most.
There are several reasons why a car’s AC can leak or drip water into the passenger compartment. First it’s important to understand that water dripping from under the car when the A/C is on is normal. It’s only when the water drips on the inside of the car there’s an issue. Varying amounts of water dripping (condensation) under the car is to be expected, depending on the level of humidity in the air. The higher the humidity, the higher the volume of water can be seen dripping under the car from the evaporator drain tube. I’ve actually had customers that complained because they thought that too much water was dripping under the car after an AC repair. On several occasions customers would say “It never had that much water draining out before.” It’s funny how some car owners pay closer attention to certain things after a repair has been made. After explaining that it’s a normal for condensation (water) to accumulate on the evaporator fins, drip to the bottom of the case and run out the drain tube; only then they understand that there’s not something wrong.
One of the most common causes of water dripping inside the car is because of a clogged drain. If the evaporator drain becomes restricted, the water backs up in the HVAC (Heating, Ventilation & Air Conditioning) case. The case is designed to allow water to travel to the bottom and out the drain tube. The case is not designed to be completely water tight in the event the drain becomes clogged. Sometimes if excess water remains in the case, some of it can blow out of the AC vents. In extreme cases the water can damage the blower motor and/or short out the blower resistor. Usually the blockage is caused by debris in the case, like leaves or dirt. Many times the evaporator drain can be cleared by blowing compressed air into the drain from the firewall side. A metal coat hanger can also be used to stick into the drain tube to loosen the debris and allow it to exit with the water.
Another common cause of water entering the passenger compartment can be from a faulty seal which is located between the HVAC case and the firewall. The water can drain out of the tube (unrestricted) – then run back to the firewall and leak into the passenger compartment, underneath the carpet. This is actually quite common with vehicles that don’t use a rubber “L” shaped hose on the plastic drain tube. Chrysler dealers (especially when vehicles are still under warranty) will sometimes install a simple rubber o-ring onto the plastic drain. When the water starts to run back on the underside of the tube towards the firewall it meets the o-ring. When water touches the o-ring, that causes it to drip downward instead of traveling the full distance to the firewall and entering the passenger compartment past the faulty seal.
The Chrysler Sebring pictured at the beginning of this article has a separate drain tube that attaches to the firewall which prevents the o-ring fix from being used. The problem is that the drain tube attaches to the firewall and NOT the drain on the case. If the seal is bad, the water can leak inside the car regardless of the firewall mounted hose. In cases like that (the Sebring and also Stratus) – the evaporator case has to be removed and the seal replaced or resealed. On every evaporator I replaced (any make/model) – I would always apply “Right Stuff” sealer to the bottom portion of the seal, to prevent a water leak after I’ve had the case out. Having to remove the case to repair the leak is obviously the worst case scenario, but sometimes it can’t be avoided.
Another cause of water leaking into the passenger compartment can be the HVAC case seams simply leaking. On the Chevrolet Cavalier and Cobalt the HVAC case uses a groove and tongue system that has no sealer from the factory. If the case becomes slightly distorted, it can allow water to blow past this seam and leak onto the carpet near the drain. The evaporator case has welded plastic rivets, that holds the housing together; if the case is removed, the welds have to be drilled out to separate it. When the case is apart, a sealer can be used like silicone or Right Stuff (my preference) in the seams. When putting the housing pieces back together screws are installed in holes that are provided. It is possible that the seams near the drain can be sealed externally with a sealer on the Cavalier or Cobalt. It is necessary for the sealer to work, that the area it is being applied to is completely dry. It’s also necessary to allow plenty of time for it to dry before running the AC.
Question: I have a Mitsubishi that leaks water on the driver’s side and wets the carpet. Could this be condensation from the air conditioner? If so how can I repair the leak?
Answer: The evaporator drain is on the driver’s side on some Mitsubishi models. If the drain seal is bad the water can run back inside, usually underneath the carpet. On the Mitsubishi Endeavor, the drain cannot be seen from the outside of the vehicle. I have been successful with the Endeavor and other Mitsubishi models, resealing around the drain without removing the case. 1. I removed the gas pedal and pulled the carpet back. 2. Removed the bad seal from around the drain with a pick. 3. Dried the area thoroughly with compressed air. 4. Wore latex gloves and applied Right Stuff, forcing it around the drain and through the firewall. – A bit messy, but definitely worth a shot before removing the entire dash and case.
Question: Can I fix the drain with the use of silicone instead of Right Stuff?
Answer: Probably. However I prefer Right Stuff because it sticks to surfaces better and dries harder, more like rubber when it is fully cured.
Question: I have a 2006 Dodge Caravan, should I try adding a hose to the drain or would the o-ring fix work for my van?
Answer: The plastic drain, will not accept an “L” shaped rubber hose, due to the slot that is cut out in the bottom part of the plastic tube (which is part of the case). The o-ring fix for your van should work well to prevent AC condensate from leaking back into the vehicle under the carpet. According to Chrysler TSB 24-001-06, this should work on all Dodge Caravans and Chrysler Town and Country vans from the year 2001-2006. The dealer/factory/OEM part number for the o-ring is 68001994AA, although any o-ring that fits over the plastic drain tube should work.
The tips in this article are very basic and NOT intended to be a complete guide for servicing your AC system. Please refer to a repair manual for further instructions.
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Rigoberto Garza :
Date: May 15, 2010 @ 7:28 pm
i have a 2001 cavalier and it drips bigtime in the passenger carpet..what should i do? some people are telling me that there is a drain plug? clogged line? help me?
David :
Date: June 25, 2010 @ 7:23 am
Thank you, The information I found here was very informative. I think you just saved me a lot of money for something I can do myself.
Just want to say THANK YOU!
Denise :
Date: June 28, 2010 @ 12:57 pm
Thank you! Very helpful. Whenever I use my A/C on my ’03 Stratus, my drivers side floor gets soaked. I’ve taken it in before, and all they have done was “unclogged the line” but it’s still doing it. I will be taking it in again along with your post.
~Denise
bob woodie :
Date: July 8, 2010 @ 3:47 pm
I drilled the hole and found the drain clear,its behind the drain that is leaking.what do you think I should use to seal behind the drain? where would I find this stuff called right stuff? I would like to give you kudos for helping people fix there problems.Oh bye the way my car is a 94 grand cherokee,any ideas would be great.Thanks woodie
dennisb - Auto Tool Sales :
Date: July 8, 2010 @ 6:57 pm
Not much time to spare at the moment, but Right Stuff (sealant) can be found at most parts stores.
roy gott :
Date: July 11, 2010 @ 11:37 am
i have a 2007 chevy uplander that is leaking. i have tried a coat hanger and an air compressor. it still leaks. if you pull the carpet and padding up on the floor board going up the firewall there is another rubber pad and it is soaked. what can i do?
dennisb - Auto Tool Sales :
Date: July 11, 2010 @ 12:39 pm
Excerpt “Another common cause of water entering the passenger compartment can be from a faulty seal which is located between the HVAC case and the firewall. The water can drain out of the tube (unrestricted) – then run back to the firewall and leak into the passenger compartment, underneath the carpet. This is actually quite common with vehicles that don’t use a rubber “L†shaped hose on the plastic drain tube. Chrysler dealers (especially when vehicles are still under warranty) will sometimes install a simple rubber o-ring onto the plastic drain. When the water starts to run back on the underside of the tube towards the firewall it meets the o-ring. When water touches the o-ring, that causes it to drip downward instead of traveling the full distance to the firewall and entering the passenger compartment past the faulty seal.”
joseph :
Date: July 20, 2010 @ 12:38 am
2007 nissan pathfinder water leaking iside the passenger side. It only happens when the AC is on. I already cleaned the drain hose that is attached to the firewall, but it’s still leaking. any suggestions?
Ludwig120 :
Date: July 22, 2010 @ 2:38 pm
I have a 1999 ford fiesta trend, and there is some water spraying onto the carpet on the passenger’s side.
any idea what might it be?
Ray Saenz :
Date: July 22, 2010 @ 9:50 pm
Have had this problem on 03 Caravan for several years. Great help–the best information I have found on this seemingly well known problem that dealers will not take care of.
Thank you much.
Whitney :
Date: July 27, 2010 @ 10:40 am
I just had body work done and with that got a new compressor, fan, clutch, etc. The AC has a fresh charge. Went on a long trip in NC and had dripping from the 2 center vents and dripping in the passenger floor. Took it back to the shop and they said just condensation????
dennisb - Auto Tool Sales :
Date: July 27, 2010 @ 10:52 am
Whitney, I would see if they can arrange for the condensation to drip OUTSIDE the car! It is normal for condensation to drain off the evaporator, but obviously it should drain out the bottom through the tube. If the drain is clogged, water can blow through the vents and out the seams of the case,
Rock :
Date: August 30, 2010 @ 9:23 pm
1996 Honda Accord w/ Water Dripping (a bunch) on passenger side. I thought the drain line was clear, but will try the compressed air idea. Any idea what it takes to remove the black plastic box under the glove box? This box has the drain attached which goes through the firewall. Not sure where the water is coming from, but seems to dump out w/ a hard left or right turn.
Thanks for the info., it was helpful.
dennisb - Auto Tool Sales :
Date: August 31, 2010 @ 12:37 pm
Rock, Try the tips in the blog, sounds like the drain is clogged.
To remove the “black box” (evaporator case) may be more involved than you are prepared for. Removing the refrigerant is required prior to removal. I recommend getting repair manual information before attempting this. See our repair manual info page linked at the top of this page.
matt :
Date: September 1, 2010 @ 11:50 am
What do I do? I have a 1997 chevy malbu and is leaking on passenger side.
dennisb - Auto Tool Sales :
Date: September 1, 2010 @ 12:21 pm
Matt, you may find some of the information in the article above helpful.
Jason :
Date: September 13, 2010 @ 6:46 pm
I have a 99 Montana which is dripping water into the front passenger floor, right under the inside blower. Do you have any advice on unclogging something…? I can’t seem to find the source of this water. Also, (possibly) related is now every time I turn left, I hear ~scraping~ noises out of the blower compartment behind the glove box. Would appreciate any help. We are in Louisiana and run A/C on recirculate nearly every day. Thanks!
dennisb - Auto Tool Sales :
Date: September 13, 2010 @ 7:35 pm
Jason, sounds like a clogged drain like mentioned in the repair article. The scraping sound most likely is the water touching the blower cage – the water level could rise on one side a little when taking turns. The blower drain tube should be visible on the engine side of the firewall on most cars. refer to the article for suggestions on unclogging it.
Zach :
Date: September 25, 2010 @ 1:22 pm
i have a 2001 nissan pathfinder and i leeks on the passenger side floor bord and im not shure were the drain hoes is located
jean :
Date: September 26, 2010 @ 12:55 pm
I have a Jaguar xtyppe 3.0 and I have had a problem with water gushing out onto the passenger side carpet and then runs to back floor as well. (lot of water) No smell to this water, the mechanic states it’s from an animal getting up inside and causing the problem. After only less than 10 days out of shop again- the water is pouring out again. I live in Florida. What specifically needs to be fixed? I am thinking the leak is other than what he is saying. Thanks for any insight.
dennisb - Auto Tool Sales :
Date: September 26, 2010 @ 1:40 pm
Wow Jean, the animal must have drank a lot of water! Just Kidding.
If leaves or debris from an animal making a home in your evaporator case is present, it could clog the drain. When the drain is cleared, the debris could make it’s way back down into the drain and stop it up again. Sometimes the case may need to be removed and disassembled for cleaning. Other times the blower motor can be removed to access the trash inside the case for cleaning. Hopefully, the blower can be taken out and a shop vac can remove the debris. The blower motor labor on most cars is a lot less involved than removing the entire case. Good Luck
Jae dog :
Date: May 22, 2011 @ 3:15 pm
I have a dodge caravan 01. Water is coming in passenger side corner when ac is on. When I check the under carriage I see water dripping under near engine and also leaking out from under passenger door? Please help dealer said it was a clooged hose that they supposedly fixed. Jaw dog
dennisb - Auto Tool Sales :
Date: May 22, 2011 @ 3:37 pm
Most likely the gasket between case and firewall.
tay :
Date: June 23, 2011 @ 2:58 pm
i have a 98 toyota camry. my floor boards are soaked. i’ve taken a hanger and drained it. it helped for about a week. could something else be wrong?
dennisb - Auto Tool Sales :
Date: June 23, 2011 @ 3:01 pm
Tay, the fact that it helped for a week indicates that there was a blockage. The evaporator case may need to be taken out and cleaned more thoroughly. Good Luck.
Irene :
Date: June 28, 2011 @ 11:13 am
I have the same problem with my ’07 GMC Acadia, but can’t seem to find a drain hose – can you tell me if it has one, and where I should look? Also, by the time I discovered the water problem, my fan motor has been affected. at first (before I discovered the water problem), I could get it going by giving it a spin, but now, it won’t work at all. Is it possible to replace the ‘brushes’ in it? by the way, I’m a 71 yr young woman, which goes to proove to you’re never to old to learn *& repair!) thanks for the help!
dennisb - Auto Tool Sales :
Date: June 28, 2011 @ 12:03 pm
Irene, Thanks for the comment. It is common for blower motors to fail when an evaporator drain has been restricted for awhile. I’ve seen water mist though the vents before, because of a stopped drain – all that water is not good for electrical parts. I’m not aware of a brush or rebuild kit for the blower motor. You could check with a parts store, but my guess is that they will just have a replacement blower assembly available. Also be sure to check the electrical contacts where the blower pigtail connections are. The blower module (or resistor) can start to melt down from too much draw or poor connections. I’ve seen the plug melted so severely that it could not be unplugged. With the blower motor removed, look for debris like leaves. Remove with a shop vacuum. Also, it may be possible to flush the remaining dirt from the case with a water hose. This may unlodge whatever is stopping up the drain. The drain hose should be located on the outside of the firewall and may be difficult to access. Look for it on the passenger side in the eng. compartment. 71 huh? That’s great! Good Luck.
Danny :
Date: July 9, 2011 @ 2:35 pm
I have a 03 Toyota corrola and the ac leaks on the inside passenger side. I took it to a mechanic last year and he blew underneath the car with compressed air and debris came out and water. Now, it is happening again. What can I do?
Thanks!
dennisb - Auto Tool Sales :
Date: July 9, 2011 @ 3:49 pm
Danny, AC water leaks are common if the drain is clogged. Frequent parking under trees will cause debris to find it’s way inside the evaporator case and clog the drain. This can happen even faster than if never parking under trees. Although, simply driving down open roads, pollen and other small particles can enter the fresh air intake for air conditioning. Sounds like it’s time to clean the drain and park AWAY from trees! Good Luck.
John :
Date: July 10, 2011 @ 7:38 pm
I have as 2002 Mitsubishi Lancer. When the AC is turned on and I turn, water comes flooding onto the passenger side floor, I can hear the water gushing from inside the car. Do you think this may be from a loose hose? ALso when the AC is on, I can feel a dramatic decrease in “pickup” when I hit the gas.
Julie :
Date: July 21, 2011 @ 10:16 pm
I have a 2001 Toyota Camry. I noticed when I got the car a few months ago that the a/c leaked on my foot when i was driving when I left it on too high for a while after the car was cooled down, well after a big storm behind my drivers seat has been soaked, i have soaked up 6 towels in the past few days with the water and it still keeps coming. I recently noticed that under the mat of the drivers seat is also a little wet, not as wet but wet. when i pulled the mat out of the back seat a few days ago it was pouring out water. I’m going to try to clear the line this weekend, but would it really produce enough water to soak my back seat create like puddles almost in the back?
dennisb - Auto Tool Sales :
Date: July 22, 2011 @ 6:46 am
Julie, it sounds like there could be two DIFFERENT problems. The AC drain water can travel underneath the carpet, but since you have such a large volume of water in the back and it was after the storm; the majority of it is most likely from the rain. The AC drain water leak is not related to the leak that happend during the “big storm”. The A/C leak only happens when the AC is on and the other leak is from rain. I would fix the AC water leak and check the outside water leak separately. Outside water like rain (or from a car wash) can leak from a window or door that was not closed all the way. This can be a one time occurence, when one or the other just isn’t closed all the way. There could also be torn (or worn) weather seals, which are also called “body seals” or door seals. The seals mounted on the car are body seals and the the seals attached to the doors are called door seals. Also check window seals and adjustment of windows, especially windows that don’t have frames encororated into their designs. (Don’t even get me started on convertibles.) I would inspect all the the seals closely to make sure they are all in good condition and make sure doors and windows don’t leave any gaps when they are closed. Checking leaks with a water hose may be the next step. However, fixing water leaks (if not an obvious bad seal) can be very frustrating. In fact, most technicians hate em! Many dealerships call an outside guy in, (sublet a specialist) to work on water leaks. At the last shop I worked at, he was the “Water Doctor”. A rare breed. It takes a lot of patience and experience in many cases to deal with outside water leaks (they also deal with excessive wind noises). Hopefully your problem is something simple, I went into more detail, in hopes of helping not just you but maybe other readers too. Good Luck.
Julie :
Date: July 22, 2011 @ 11:08 am
Well I thought maybe the sun roof wasn’t sealed totally but then the water wasn’t going away and the stuff that was on the floor on my back seat was wet from the bottom up not bottom down and my seat wasn’t wet or anything so that didn’t make too much sense. I am going to take it to the garage here shortly and show them the article and the comments, hoping that I can just ask them to do it and they will not charge me a ridiculous amount. Thanks again!!!
dennisb - Auto Tool Sales :
Date: July 22, 2011 @ 11:20 am
Julie, sun roofs have a whole other set of problems. Besides the seal, a common issue with them can be the drain. The drain can get clogged and cause a water “back up”. The drain is behind the headliner and may go down behind the pillar trim. There actually could be 4 drains exiting from all four corners of the sunroof track. So, it could be that the water leaked behind the trim and underneath the carpet. Good Luck.
Al Hargadon :
Date: July 26, 2011 @ 9:51 pm
So where can I take my 2005 Sebring convertible that’s near Orlando …… I have squeezed the drain tube at the firewall and nothing appears to be clogged. I just recently removed all the carpet and within 30 minutes of running the AC water starts leaking on the passenger floor.
dennisb - Auto Tool Sales :
Date: July 27, 2011 @ 6:39 am
Al, I don’t have a specific shop to recommend in your area. In your case, you may want to check Angies List or ask friends for a recommendation.
However, I usually recommend to car owners to find a repair shop before your car is in urgent need of repair. The easiest and least stressful way to try a shop’s services out, is to schedule your car for an oil change. By scheduling your car for a simple service, you can get to know the place, see if it seems trustworthy, organized and professional. Look for ASE certifications or dealer training certifications while your there. Ask about their other services and conditions of warranty on parts and labor. Good Luck.
Darren Trueman :
Date: July 31, 2011 @ 11:17 am
I have a 2007 Jaguar XK and the water leaks from under the glove box in the passenger side. I’ve managed to get my head under there and can see some of the coolant lines but can’t replicate the leak while I’m under there. Could this be condensation from the line or do you think it is a drain or seal problem as seems to be the problem in most of the other cases. The water can reall y leak when I crank up the a/c? Thanks for your help.
Alex Tarampi :
Date: August 8, 2011 @ 5:25 pm
i got a mitsubishi lancer es 2001 my problem is it was leaking on the blower side. I had changed already the blower because it didnt work before due to leaking or got burned. What is your analysis that cause the leak on the system. Thank you very much if you could email me ther procedure to troubleshoot it.
More power
dennisb - Auto Tool Sales :
Date: August 9, 2011 @ 6:37 am
Alex, clogged drains and/or bad seals are still the leading causes of evaporator water leaks inside the car. Start the car up and look underneath the case and you should be able to pinpoint where it’s cominig from. Good Luck.
Ted :
Date: August 11, 2011 @ 3:44 pm
I have a 94 Honda Accord the AC started leaking after they worked on my fans and had taken the dash out for some reason. It’s leaking inside on the floor, passenger side and I think on the drivers side wife said she felt a drip on her leg, don’t know about that for sure but do know it leaks on passenger side as carpet got wet.
dennisb - Auto Tool Sales :
Date: August 11, 2011 @ 5:31 pm
Ted, that’s easy. I would take it back to whoever worked on it. Good Luck.
Ted :
Date: August 12, 2011 @ 9:33 am
OK thanks, I went ahead and found the tube that comes out and stuck some weed eater line up it and about a half glass of water came out. Hopefully that did it. I’m not too crazy about taking it back to those that worked on it before.
Thanks again,
Ted
Lyle :
Date: August 24, 2011 @ 1:17 am
Hi, I’ve been reading your blog and Q & A which I find extremely helpful. I have a Honda 93 Dx Hatchback which recently went through an AC overhaul- after a couple of months I started seeing water trickles which suddenly became gushes. I brought it back to the shop and they worked it out, they said I had a faulty housing for the evap and they did a couple of modifications on it, but after that- I still see trickles sometimes, not a major leak but is this just condensation?
dennisb - Auto Tool Sales :
Date: August 24, 2011 @ 6:52 am
Lyle, Don’t overlook the possibility of a restricted drain. If I were checkng the car, I would look to see where the water is coming from (inside leaking out or condensation build up on the outside of the case). Any water you find will be “condensation” however if it’s leaking from the inside of the case there’s a problem. If water is building up on the outside of the case from humid air contacting the outside of the cold case resulting in condensation and a drip; there’s not much you can do. The evaporator may be contacting the inside of the case (instead of having an insulating barrier) aggravating the problem. Good Luck.
brenda :
Date: September 5, 2011 @ 9:48 pm
water leaking when i hit the brake on my feet..i have a van
dennisb - Auto Tool Sales :
Date: September 6, 2011 @ 6:18 am
Brenda, if I were checking it I would try cleaning the drain. Good Luck.
Pam :
Date: September 8, 2011 @ 10:07 am
2007 Chev Uplander, carpet soaked on driver and passenger floor. We can’t find drain tubes. Please help. Thanks
dennisb - Auto Tool Sales :
Date: September 8, 2011 @ 11:20 am
When running the A/C look for dripping water from the passenger side exterior of the firewall (on the engine side). Unless it’s stopped up completely there will be some dripping which will lead you to the drain. On the 2007 Chevrolet Uplander, it doesn’t have a rubber hose, just a plastic drain tube. It’s hard to see due to the firewall insulation obstructing the view. It will be easiest to see from underneath the vehicle. As always, be careful around hot exhaust pipes and only get underneath a raised vehicle that has jack stands in place for safety. Good Luck.
Jason :
Date: September 11, 2011 @ 10:50 am
I have a 2006 chevy cobalt, its leaking, inside from the ac on passengers side, got it drain and it still leaking, what can it be? How can I fix it? Thanks
dennisb - Auto Tool Sales :
Date: September 11, 2011 @ 12:53 pm
Jason, as with any car with this problem it requires eliminating the stopped drain issue and then seeing where the leak is coming from. If the case has to come out like I described in the article for Cobalts, it wold definitely be beyond the skill level of most do it yourselfers. You may however apply some sealant to the grooves without dis-assembly providing the leak area (after you pinpoint it) as long as it is accessible and DRY when sealant is applied. Although, the best way to seal up the HVAC case is the way I said in the article. Good Luck.