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Mice Nest in Ductwork

2013 Chev. Equinox, 20k miles. First thing this morning noticed bad smell in the Equinox with the AC on. Pulled out Cabin air filter at lunch time and it was nearly clogged with hair, some mouse poo and a pile of maggots. Inside the filter housing it looks like a lot of hair. I’m going use a shop vac to clean out as much as I can from the filter opening. I am not sticking my hands in there.

I didn’t see any obvious ways in, the cowl screen is properly installed. This has never happened to me before but I guess there is a first time for everything. Any suggestions on how to get rid of the smell. After I clean out the duct work as best I can I’m going to spray Lysol into the windshield cowl with the fan running.

Ed B,

Here’s the bad news: There’s probably crap in the squirrel cage blower chamber, especially if the mice chewed through the filter.

The good news is that of all the chambers in the HVAC system, it’s the easiest to get to.

The bad news is that the fan tends to shred nests and the food mice bring in, and shoot it over into the next chamber, which is the evaporator for the air conditioner.

The worse news is that if there’s any food storage going on in there, that food is going to enter the evap chamber as a fine spray of food particles, and it’s going to form a layer of growth medium on the bottom of the chamber. Then when you run the air conditioner, the evaporator is going to drip water on the growth medium, and you’re going to get more maggots and a smell that isn’t going to go away without a lot of work - and unless you do it yourself, it’s going to be expensive. If you do it yourself, it will only cost you a bottle of Chlorox spray, some water, and several hours of rather disgusting work.

What I’m driving at is that before you run the HVAC system again, you should make sure there isn’t anything in the blower chamber. If you dive under the dash, you should see the motor - it’ll have a wire harness hooked up to it, and be held in with 3 small bolts. Just unplug it, then unscrew the 3 bolts, and it’ll drop right out. Make sure it’s clean (some dirt may be on the blades, but no mouse hair or food bits). If there is crap in there, and you caught it in time, it shouldn’t have blown much of anything over to the evap chamber, which will save you a lot of disgust and headache.

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Thanks for the info. I may have got lucky, the mice never made it through the filter. I took out the filter and was able to remove the nest with my shop vac. I didn’t see any food stored just nesting material. I sprayed a 1/2 can of Lysol into the windshield cowl vent while the shop vac hose was attached to the filter opening. I’ll keep my fingers crossed.


I’ve used Febreze Air Effects “Pet Odor Eliminator” to help with “dead mouse” smell.

I wouldn’t stick my hand in there either.

Kids have smaller hands…thats what grandkids are for.

“Who wants to go for icream after we fix Pappies Truck”


I would advise that the OP only work on that infested area of his truck while wearing a respirator and exam gloves, and that he cleans out those ducts with a dilute bleach solution in order to sanitize the area. In case anyone thinks that this is excessive, Hantavirus, which is spread by the droppings and urine of several different species of mice, is an extremely serious infection, and is not confined to the American Southwest, as was once believed.

Subsequent to its discovery in The Four Corners area, this rodent-borne infection has been detected as far away as Florida and a rural area of NY state, so it is very possible to contract this infection in many parts of The US.

After using the ShopVac, I would advise sanitizing its hoses and tank with a dilute bleach solution also, as the closed-up vac’s tank could be an ideal place for that virus to multiply.

Take a look at this information from the CDC:

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I agree with VDC on this. There might even be times when goggles are called for, if you are under the dash looking up while disassembling ductwork, I would not rest easy until I had done enough disassembly and cleaning and inspection to be sure nothing remains to be blown about.


Excellent advice as usual. I remember reading about Hantavirus back in the 90’s, I had no idea it had spread so far. I thought I was being overcautious last night, but perhaps not. I had gloves, but no respirator when I cleaned the out the cabin filter housing. It does not appear the mice made it past the filter. I did not touch the nest and washed my hands several times during the procedure.

My procedure was to vacuum out the nesting materials. After this I sealed the vacuum nozzle to the filter opening with duct tape, closed all the dash vents and ran the shop vac for 20 - 30 minutes to remove any remaining debris. During this procedure I sprayed Lysol into the cowl vent several times. After that I buttoned up the filter housing, opened the dash vents, and ran the heater blower to get the Lysol spread through the duct work.

This morning, I kept the fan on high and the heat on to clear out the Lysol smell. So far, so good.

Fortunately besides bleach, Lysol spray or cleaner is recommended for cleaning up hantavirus contamination. I will clean the vacuum hose and tank with Lysol cleaner tonight.


Ed B.

You’re very welcome, Ed.
Stay healthy!

I didn’t see any obvious ways in, the cowl screen is properly installed.

Sorry to hear this happened on such a new car. I’ve had cars virtually destroyed by mice getting into ventilation systems.

By cowl screen do you mean the plastic piece on top of the cowl area with the wipers below? If so, you should know that the entrance to the blower is a virtually unprotected snorkel that sticks up above the cowl under this trim piece with the screen. Mice crawl right up the side of the cowl where the water drains down to get under that trim piece. Once there, they have unfettered access to the blower entrance. You can look from below with the glove box lowered and cabin filter removed or peer down through the screen from the outside to see the snorkel. I temporarily remove the plastic trim piece and then you have access to put a section of steel screen over the snorkel to keep them out. Fold it over the edges and wrap a piece of bailing wire or a tywrap around it to keep the screen in place. Then replace the trim piece and never worry about it again.


“Mice crawl right up the side of the cowl where the water drains down”. Thank you, I never would have made the connection even it seems obvious. Now I have a weekend project.

To replace the cabin filter on my 03 Taurus I have to remove the passenger side cowl cover. The filter sits in the top of the cabin “snorkel” under the cowl. In light of your comments this is actually a good design by Ford.

Ed B.

Drove home from work with the windows up and the AC on. Just a faint trace of Lysol and no musty smell with the new cabin filter installed. Will try and install a screen on the air intake/snorkel under the windshield cowl.

Ed B.

Good news! Give it a week or so and then when it’s very humid… if it doesn’t stink then, you’re golden.

We haven’t discussed the real problem, have we?

Where did they get in? If you have reason to suspect that they got in, in a garage, you need to do something to keep them out. It’s harder if the car is parked outside, because you have to take it out and unplug it each time.

I have a 2850 square foot house in rural Mexico. The worst pests are scorpions, but rats and mice and lizards are also a nuisance.

While I have no financial ties to Steren, I find their ultrasonic repellers do the trick. Google. They look like speaker boxes with a power cord. I don’t know current price, but they should be $30 or less. Those tiny ones from the construction stores are useless.

Their recommendations for area covered are pure fantasies. For my house, I need 8 of them. For a two car garage, you might need 2 or 3. Keep them out of water, but they take very little power so you can leave them on all the time.

We get a scorpion once in a while, but he is usually moving slowly, and I give him the grown man standing on him test; most fail. Very few rats or mice, and most of them act like they are dying, because they are. Lizards run very fast until they get close to the device, then freeze up solid, can’t even move. Don’t use around similar pets!

Just an update after a week. Took a 700 mile round trip to visit colleges. No issues, no smell. I guessing the mice vacated the premises before I found the nest. I got lucky this time. Again, thanks for all the suggestions.

Ed B.

Yep, I knew someone with a dead mouse “in there somewhere.” He chose not to tear the dash apart and the smell was there for months (tempered by pine trees hanging on the mirror).

I had the same issue with my 2012 Equinox. I removed my cabin air cleaner and found evidence of a nest on the top of the air cleaner. The nest wasn’t that dirty, but smelled bad. So did the filter. It didn’t seem to drop down into the fan and I carefully dug it out with a large screwdriver. Unfortunately the nest material was white with some grey and looked like sound deadining material. No evidence of passing past the vent grate at the base of the windshield. I didn’t find the water path mentioned above. I used my iPhone to slip into the slot for the cabin filter and take a bunch of pictures above and below to ensure no other trace of mice or nest material. I sprayed some eco disinfectant in there, bought a new hepa filter, and took a drive. Seems OK. We will see in a couple of weeks.

Got me again. I didn’t notice it was 6 years old.

For others anyway, agree on the safety issues. Might want to try a full cleaning like you would clean a dryer vent. Duct tape or whatever the shop vac on the open filter area, and shoot compressed air down through the defrost vents etc.

Me too wondering if they got in from the outside or the inside. Feel anything on your leg while driving? At any rate thanks for ruining my supper with the stuff you found.

OP here, I was lucky, the mice never got past the filter. I’ve had no issues since the the cleaning.

Ed B.

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I just removed a nest and dead rodent from the same location - above the cabin air filter. This was in our 2015 Honda CR-V. We also noticed a terrible smell (a dead rodent smell) when turning the air on and couldn’t find trace of any cause within the cabin, under the hood or around the wheel wells. Getting behind the glove compartment and pulling out the cabin air filter, I noticed the brown hair and a lot of cotton poking through from the compartment above the filter down into the space with their filter was. I had to reach in their with a butter knife and my gloved finger to pull back the flap and pull the corpse and the nest material out. Based on the tail it was probably a rat, but not 100% sure.

I just can’t imagine how it got in that compartment above the air filter (which was intact still) and nested!