Bad smell in cabin, rat urine and feces in cabin air filter

I experienced a bad smell in the cabin, particularly when first switching on the ignition, which of course causes the cabin air fan to start running.

I first noticed it sometime in or about 2015. I thought it might be caused by mold in the air conditioning, so I checked the drain, but it was clear. I tried turning on the heating to full high for a while, but that didn’t help.

On 1-14-16 at 42,760 miles I replaced the cabin air filter (not due until 60,000 miles). The old one looked like it had got wet and there were rat feces on it. I wondered how rat feces could have got there.

The smell continued, and on 3-19-18 at 47,918 miles I again replaced the cabin air filter. This time I took a picture (I have kept the filter):



There were rat feces in the pleats of the filter, a smell of rat urine, and there was foam material from the inside of the car. Presumably the rats had been chewing it to make a nest. They had also been chewing on the filter material.

I removed the blower fan assembly that sits below the filter, and found what looked like and smelled like partly dried rat urine. It is visible on the base below the fan blades in the next picture:



I researched online and found that the Tacoma has had an ongoing problem with water getting into the cabin air intake from the windshield. I found there is a Toyota Technical Service Bulletin T-SB-0061-12 for 2005–2012 models to replace the cowl, which is a plastic ledge at the base of the windshield, with a redesigned cowl. I went to Maui Toyota on 5-3-18 and showed them the filter. I told them that I was aware that the design of the original cowl was defective, and requested that they perform this TSB, and investigate how rat urine and feces are getting into the filter. I told them that even though my vehicle was out of warranty, this was an original design defect, and I asked that this work be done at no cost to me. I told them I consider the rat urine and feces to be a serious health issue that Toyota should be interested in understanding and correcting.

Maui Toyota documented my visit, and referred me to Servco Toyota on Oahu. They told me that Servco Toyota was the conduit to Toyota USA. I called Servco Toyota the same day. After a number of phone conversations, on 5-21-18 Servco Toyota told me that Toyota USA had no other reports of rodent issues and would not do anything for me. Servco Toyota also said that they believed that performing the TSB would stop water getting into the cabin air filter, but would not resolve the rat issue. On 5-23-18 Maui Toyota called me and offered a 20% discount on a replacement cowl, if I wanted to replace it myself. As it turned out, I did not replace it.

On 5-24-18 at 48,398 miles I removed the cowl and found the new filter again contaminated with rat feces, and the filter material had been chewed all the way through. The next picture is taken from above looking down into the cabin air intake, and the following picture is the filter after removal. I have again kept the filter.





I found that that the top of the cowl is drained by holes where the windshield wiper drive shafts go through the cowl. The water collects in the space under the cowl, which in turn is drained through large drain holes at both ends, down into the fenders above the wheel wells, and to the ground.

The next picture shows one of the large drain holes on the end of the cowl on the passenger side, and another large hole. The driver side looks exactly the same (mirror image). I think the rats were getting under the cowl and into the cabin air intake through one or more of these holes.



I cleaned the blower fan assembly, the cabin air intake, and the inside of the cowl, and replaced the cabin air filter.

I made screens from ¼ inch mesh to keep the rats out of the space under the cowl. I installed them on both sides. I made paper patterns for the screens (I had to cut wide around for some of the folded parts):



I secured them with two plastic clips at the top through factory holes that are not used for anything. This one is on the passenger side, the one on the driver side is a mirror image :



I also made and installed a screen over the cabin air intake to keep rats out if they somehow get around the side screens. This screen is also secured by two plastic clips at the front through factory holes that are not used for anything. The following picture shows the screen over the cabin air intake:



I looked at pictures of the redesigned cowl, and the changes seemed minimal, so I reinstalled the original cowl with ¼ inch diameter auto glass sealant strip in the channel that fits over the edge of the windshield. This should seal the edge and keep water out of the cabin air intake. I have since washed the car with no water getting into the cabin air intake.

Since rats carry disease, I consider this a serious health issue for all the other owners of these vehicles. I have forwarded this information to Toyota USA and the Hawaii State Department of Health, the U.S. National Highway Traffic Safety Administration (Complaint number 11100056), and Consumers Union in the hope that they can pressure Toyota USA to do the right thing and correct this issue for all owners.

 

I mean, how is it Toyota's fault you have rat problems?

 

Good solutions. Several here have posted similar.

A repellant in the engine bay is helpful too. Because thats were they will go now that you have thwarted their fav spot. And a wire harness gets pricey fast.

I use the toe end of old panty hose (yours or the wifes, doesn't matter) with 2 cotton balls inside. Apply peppermint oil to the cotton every couple of weeks.

I hang one by the coolant overflow and one by the master cylinder

Another tip for when the cowl is off. Turn it over and hot glue fiberglass window screen on the back side and trim with a razor. It will keep leaves and needles from clogging the drain system up.

 

it's not Toyota's fault I have rats on my property. Many, many people do. They are hard to get rid of.
However, in my opinion, it is a design defect that they can get into the cabin air filter, and that is Toyota's fault.

Good tip on peppermint oil, thanks Bill. I will do that.

 

I don't want to sue.
I posted this because I want to help any in the Tacoma community who have the problem.

 

IMO it is a design defect to not have a cover that keeps animals and debris out of the interior of your vehicle. Those same cowl holes allow debris to collect in the fender bottoms, perfect for causing rust.

I have owned several older Toyota trucks/Tacomas and all have had some methods in place to exclude critters and leaves/crap. They just decided to delete it for some reason when they designed the 2nd gen. Probably saved them $.05 per unit in manufacturing costs on a truck they charge a lot more money for.

I had to pull the whole bottom of the dash out of my truck and use an inspection cam and grabber tool combo to get fruit out of the heater box after a critter made itself at home. Have also had several costly repairs caused by critters snacking on the soy jacketed wiring but that is a complaint for a whole 'nother thread.

 

Keep in mind that rats are not the only vermin that can create such issues.

Chipmunks, squirrels and field mice are just as bad. Worse sometimes.

We don't have chipmunks here, but fruit rats, squirrels and mice are common.

 

Had to make a screen like you did as well.

After two mice nests were found in my cabin filter,i had enough.

Here is one of the nests with dead baby mice that stunk up my truck. Had to drop the blower motor out to clean it.

Sprayed Lysol into the blower fan while running to get rid of the smell

Here is the 2nd nest

 

Thanks for the write up. I recently had a rat/mouse problem in my detached apartment garage. I originally found droppings in the garage first thing I thought of was wires in the engine bay especially with the heat after I parked at night. Sure enough I had 2 harness with just some minor chewing on the factory tape, and another harness with a wire that the insulation had been chewed with wire exposed. Cleaned and repaired it all. Sprayed foam in all the holes neighboring other garages, put poison, and traps out. Never had a problem again, but never caught the culprit. I honestly didn't check my cabin air box till about a month later (today) and man I wish I had. Rat droppings, urine, and foam from the inside wall of the air box. Easy clean. I like your screen ideas, so I'm working on making something similar. Thanks for the ideas and your write up. Also not thrilled I've been breathing what was in my filter.

 

My mom has issues with field mice at her house.
She’s found her tissues and other things chewed on inside of her Ford Escape.
She got it with a mouse trap on the passenger floor.

 

Try having a pack rat die on your cabin filter, shortly after you park your truck for 2 weeks...in the summer.

 

No thanks, this was bad enough just worrying about damage to wires or anything else..

 

It is Toyota's fault for using soy based wiring. It gives the mice/vermin/whatever a nice easy meal and a place to hide.

 

I think you are absolutely right. There is no reason to have that air intake unprotected, and this rodent issue effects a high percentage of Tacoma owners. It's a potentially costly situation, and a potential health hazard.