This seems to be a fairly rare issue, but I just wanted to share my experience and give a quasi DIY.
(Short explanation of an a/c drain blockage for the non-car people like myself)
When a car is operating normally with the a/c running, a small puddle of water will begin to form below the car - this is perfectly normal and is caused by condensation as part of the cooling process. When an evaporator drain blockage occurs, all of the water that would normally be drained to the ground begins to pool inside the car. The blockage itself is caused by small amounts of dirt and debris that clogs the end of the drainage tube.
The big problem isn't the actual leak itself, but the fact that if it progresses and is left untreated, mold can begin to form in the carpet and/or padding below (I bet the smell is not nice at all). Excess moisture inside the cabin can also negatively affect some of the electronic systems.
If it gets bad, your going to be looking at getting at least a new interior. Looking online, I was going to be down at least $1,200 just for the carpets and padding (and that's assuming a DIY project).
If you experience any of the "wet" symptoms, I strongly suggest you take a trip to the stealership ASAP. When this happened to me (2007 IS 250 with around 70K), I was already out of warranty and SOL.
There are a number of different problems (many of which are significant) that can cause water to pool inside the cabin (and many of which are not discussed here). Do not attempt to diagnose this problem or perform any repairs without the assistance of a certified repair technician. Use this material at your own risk.
It seems that the problem primarily affects some of the 2006-2007 IS 250's and 350s, along with some GS models of the same year (specific VINs are listed on the TSIBs below). I would imagine that as these model year vehicles begin to get older, many more will experience this same problem as time goes on.
Anyway, the moral of the story is that the culprit is a small rubber grommet and insulation that is placed at the end of the a/c evaporator drain. This grommet and insulation is apparently the "hot spot" for where a drain blockage almost always occurs. I can't really fathom why this grommet would have been put there to begin with, but that's besides the point.
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Wet carpet - In my case the whole carpet was soaked, but it was particularly wet on the floor of the back seat. The majority of the water leaking into the cabin actually came from the A/C vents located below the driver and front passenger seats. The A/C still worked fine though.
Water did seem to get in from other locations; however, the back seat seemed to be the primary area. Some have said that they get more water on one side of the car as opposed to the other, but mine was pretty much even.
Windshield fogging up - typically would happen when I started the car in the afternoon.
Moisture - I've heard that some have seen condensation on the inside of the car.
No water dripping below car - If your A/C is cranked for a while and no water drips on the ground, you may have a problem. On the my model it drips out under the car near the transmission. If your in an area of low humidity, you may not have much water drip to begin with, so this may be hard to conclude.
Be careful here - on mine I would crank the A/C, and water would eventually start coming out the bottom (maybe after a longer car ride). I later came to find out that water was continuing to pool on the inside the car, and was leaking out a small hole under the floorboards.
Before determining that the A/C drain is the problem, check for these other possible causes of water inside the cabin. These seem obvious, but this can save you a lot of time and $$$ if you determine if this is your problem first. Most of these are easy fixes.
Sunroof (most likely the sunroof drains and not the seal itself)
Rubber Grommets on the underbody
Lets also not forget that some cars just condensate a little bit on the inside from the A/C, and it isn't a big deal. Mine on the other hand had what seemed like gallons of water soaked in the carpets (it was hot down here in Florida so I had the A/C cranked).
Last edited by msb028; 07-15-11 at 02:09 PM..
Reason: add link
The first TSIB issued on this problem was back in 2007. The "fix" was an enormous task that involved taking the entire AC system and dash apart to replace the packing around the drain tube, in addition to the rubber grommet itself. This does not sound like fun. This was TSIB No. AC003-07.
Yes you read that right, the fix is as easy as pulling this rubber grommet out, and trimming any excess insulation that is around the end of the tube.
The instructions call for this grommet to be accessed from underneath the car, which is a much easier task than taking apart the whole dash and A/C system.
The only difficult part is that the drain and grommet is located directly above the transmission, and requires the lowering of the exhaust system to be able to have good access. Most cars have a drain tube that is in a much more accessible location, but unfortunately were not that lucky.
The 2010 TSIB instructions are actually very detailed and present pretty good illustrations; however, I would not suggest attempting this repair yourself unless you know exactly what you are doing.
I didn't have all of the jacks required, so I printed out the TSIB instructions and took them to a local repair shop. $100 and about an hour later I was good to go.
The tech at the shop noted that when he pulled out the grommet, some (but not a lot) of water immediately spilled out. Other cars he has fixed blockages on in the past typically spill out much more water. I assume that on our cars, this is due to the location of the drain on in close proximity to the evaporator. Other vehicles have longer tubing that will allow the water to drain out in other locations - this tubing will also hold more water when it becomes blocked. No big deal, but just a note to keep in mind.
If you are worried about this problem happening to you, You can probably have this service done as a preventative measure.
I had gotten the cause of the leak fixed, but there was still tons of water in the car that had me worried.
If you catch this early enough, you may be able to get away with putting some desiccant in the car. DampRid sells some hanging bags that you can just hang from the headrest of the front and passenger seats. You can probably pick these up at Wal-Mart.
It had been more than a week since I first noticed the dampness in the car, so it would probably have taken some time for the whole thing to dry.
I didn't particularly want to spend a grand on new carpets, so I decided to pull out the carpets and let everything dry. Glad I did that - a lot more water was down there than I expected. I'm note sure how long it would take before mold will start to grow - don't know that I want to find out.
The carpets held some of the water, but the majority by far was soaked up in the padding underneath. I took these pads out, and wrang them out like a towel that had been soaked in the pool. These pads took almost two days to dry on the floor of the garage. Not sure how long it would have taken if they had stayed under the carper with poor/no ventilation.
The whole process of pulling the carpet actually went a lot quicker than I was expecting. It one big piece.
The seats had to come out and I had to take apart the center console, which is kinda a hassle - but the whole process probably took me under two hours.
I let it dry out in the garage, put it back in, and I was good to go! Probably saved myself more than a grand in carpet replacement.
I had to keep looking on the bright side after all of this - at least it gave me a good opportunity for a carpet shampoo treatment!
According to the dealer history on my car, it had this happen within 20-30k miles of original ownership. Said the interior was treated, cleaned, and replaced because of the evap issue. I wonder if I got new carpet, or just padding? hmmmm.