RV Doctor: Mice messed in heating ductwork, can’t get rid of smell


Dear Gary,
Mice got into my RV so I purchased an electronic mouse repellent, which appears to be working. Here is the problem though: While in the RV, they must have urinated in the heating ducts. When I turn the heat on now, this obnoxious odor comes pouring out.

I have tried running the heat while out of the motorhome for a couple of hours at a time, yet it continues to come out strong the next time I turn the heat on. Any suggestions? —Cheryl

Dear Cheryl,
Yikes! That must be annoying! I’m guessing that there is little you can do to eliminate the odors completely. Chances are the urine has permeated the insulation inside the ducts and is now permanently entrenched. Adding heated air to the mix by running the furnace only exasperates the problem.

The only cure is to replace that section of ductwork. If your ducts are routed on top of the flooring inside the RV this task is relatively simple. If, however, you have a central distribution ducting system, it becomes more problematic.

In that case, first try stuffing crushed-up black and white newspaper pages into each duct as far as you can easily reach and then closing or taping off the ducts for two to three days. Every two or three days, remove and trash those pages and stuff new crumpled pages in there. Repeat as often as necessary. Crushed newsprint has removed fouled food odors from refrigerators in the past. Perhaps it can work wonders for mice urine as well. Check with your local pet store also; they may have urine odor products available.

Wish I had better news for you, but animal urine is definitely one of the most difficult odors to eliminate. Maybe some of our members and readers have some ideas. If so, please comment below.

gary-736Read more from Gary Bunzer at the RVdoctor.com. See Gary’s videos about RV repair and maintenance.


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Al Rodecap

I’ve unfortunately had that problem twice. There was a comment that you may have to have a technician pull the furnace and clean it. I had a fairly healthy nest in the furnace. Even with it out, there is still an odor.

You also need to clean your furnace ducts, registers, etc. Once that is done, you have a problem with sanitizing the furnace and duct work. There are 3 different solutions that can be used, Microban2, chlorine bleach, and Quaternary Ammonia. Each as their benefits and issues. Microban2 is really expensive, close to $170/gallon; chlorine bleach is corrosive (not good for the furnace; & quaternary ammonia is non-corrosive but don’t ingest it (don’t ingest any of these). I used a product called Quat-10 available at most janitorial supply houses. It not only sanitizes to a hospital infectious disease level but also deodorizes.

You need to spray it into the furnace, the duct work, and probably any surface that might have been contacted by the rodent. Keep it damp for 10 minutes, then let it dry. You can get Quat-10 wipes at the janitorial supply house as well for use on countertops.

Mice tend to follow scent trails, so hit the underside of your camper as well wit the Quat-10 spray. Once you have done that, look for any holes in the body or underneath. It only takes a hole the size of your little fingernail for a mouse to enter. They have the ability to compress their head to get in so plug the hole with steel, brass, or bronze wool (scrubbers work good) and then fill it with the Rodent-block foam sealer. If you can’t find that, look for the foam sealer in the black can as that seems to be detrimental to the rodent if they eat it. DO NOT use the DAP easy clean-up foam (water clean up) as it’s cornstarch. Instead of keeping them out, it just invites them (long story but I found out the hard way).

When you are all done, find somewhere to borrow or rent a ozone generator and put it in for a couple of days. That will finish the odor removal. Not a bad idea to do that every year anyway.

Good luck.


Sort of related question I guess? I mean, it’s not RV related, but related to the newspapers suggested as the solution to this problem.
Any idea how to get smell out of newsprint? I’ve got a bunch of old Popular Mechanics magazines from the 50’s that I found at a garage sale. They’re in great shape and I want to read them but they all smell musty and terrible. Any ideas?

Kevin Hogle

You may want to have an RV furnace technician clean out the actual RV furnace itself. Mice can get in the heat exchange itself instead of just the ducts. Anybody that had them get into a car knows that they nest in the heater core.

Bob Hansen

Charcoal Briquets also help in stinky places. place in vents or crush and place in bowls then insert.
I keep some in my fridge also.

Karen Willis

There is a product called Odoban that is very good; don’t know if it sprays far enough for your vents. I get it from Amazon, but it’s likely available other places, too.


Our local cleaning company that does carpets, etc. also offers vent cleaning services. A company like this might be the way to go.


It’s likely a dead animal. We had that happen in our travel trailer AND our cabin cruiser boat. Time will end the odor should you not be able to find the source.


Have your ducts checked out, you may have a dead body in the duct. It happened to me.


Please research activated charcoal for your problem. My in-laws used it in a rental house and it worked very well. Thanks,



You also need to check the duct work to see if the mice chewed holes in the duct work. That would alter the pressure balance in the heating system & could affect how the furnace runs.

Bill M

Our friends bought a park model next to us. The lady that had it before them had cats. In one closet the smell was horrible. Tried everything solution we could find on the internet. I suggested an ozone machine. Found one on Amazon for $75. Ran it for two hours in the closet and it removed the smell. Not sure if it will work in your situation but maybe you can find one to rent.


What’s a newspaper?


The only effective odor removal I ever witnessed was a commercial company that deodorized an entire school building following a smoky fire. They sprayed chemical deodorizer throughout the building, and set up exhaust fans at all the open doorways. (I wrote a newspaper article on it, and interviewed the technicians on site.) They explained that the treatment absorbed the odor molecules, and when it evaporated it took the smoke smell with it. The fans carried it away. So… spray a deodorizing product (Febreze, perhaps?) that will not simply mask the odor, but will combine with the urine molecules and carry the odor away with lots of duct venting. I’d check into various carpet deodorizing products.

Simply masking the odor won’t work, like the old joke in which the guest commented that her host’s home smelled like a bear had taken a dump in a pine forest. (The host had sprayed a pine-scent product to mask his flatulence.)