Animal In My Air Duct. Signs, Health Risks & Easy Removal Steps

Last Updated on July 1, 2025 by Chad Peterson

Hear scratching or smell something odd? Discovering an animal in your air duct can be alarming — and dangerous for your health and HVAC system. Learn how to check for animals, remove them safely, and protect your home with this simple step-by-step guide.

Signs You Might Have an Animal in Your Ducts

Animals leave telltale signs in your ductwork. Before you start tearing things apart, check for these common indicators:

• Scratching noises
• Bad smells
• Poor airflow
• Unexplained debris at vents

Step-by-Step Guide to Remove an Animal

If you’re sure there’s an animal in your ducts, follow these steps to handle it safely and avoid damaging your HVAC system any more than it may already be.

• Turn off HVAC system
• Inspect accessible ducts and vents
• Use traps carefully (with instructions)
• When to call an HVAC pro or wildlife expert

Health Risks of Animals in Air Ducts

Animals can introduce serious health and safety risks if left in your ducts too long. Here are a few of the main dangers to look for.

• Air quality concerns
• Possible diseases
• Electrical/fire hazards

How to Prevent Animals from Getting In

Once you’ve removed the intruder, take these preventive steps to keep your ducts clear and your home safe.

• Seal openings
• Regular inspections
• Use professional duct sealing

Real-Life Examples, My Stories

Here’s where it gets interesting! My real experiences show just how creative (and destructive) animals can be inside ductwork.

• Cat and attic duct
• Dead squirrel in furnace
• Snake story

Cat’s Destroyed Customers’ Ductwork

I’ll tell you what I would do if I had an animal in my air duct. Don’t cringe! But I’d set a trap. You choose between a live trap or a death trap.

I would start with the furnace doors. Remove them and look as far as you can up and down inside the duct work.

When I ventured into the attic, I found the large damaged duct, pictured below, with a huge hole that had been sucking attic air instead of home air. That 16-inch duct was wasting a lot of energy trying to heat or cool attic air instead of the living space.

When I changed the filter in the grill near the bedrooms I noticed the filter was clean and like new (unlike the other filter) and there was no air sucking the like new filter into the grill. The furnace was on, so instantly I knew something was wrong.

The crawl space wasn’t much better. The cats clawed and broke down the warm air ducts under the house and made a soft, cozy home among the hanging insulation. A mess of floor insulation was everywhere — a true cat haven.

Dead Squirrel In Furnace

When a squirrel, or even mice and rats, get into your ductwork, they can destroy and damage an entire system. This squirrel found its way into an electric furnace and helped short out some vital parts of the HVAC system.

This squirrel didn’t know it would cost over $800 for his funeral. There were other repairs not directly related to the nut-storing squirrel, but he initiated a series of events that led to the no-heat call.

This next customer had no cooling during one of those intense hot spells in Central Oregon. When I got there, I found the compressor dead. As usual, when a heat pump is very old, I try my best to sell a new system.

In our conversations, they told me about a rat (one of those desert rats) that had gotten into their ductwork. The lady of the house had seen it once, and they thought it had just gone away. Not so.

You can see the rat in about the middle of this image. Pretty dehydrated and shriveled up in a ball. This customer didn’t call me saying, “I have an animal in my air duct”. He didn’t know this mess was in his furnace.

Funny thing is that he is resting on the filters. This is a poor arrangement for filters. Difficult to access and replace. I have learned that the easier a filter is to access, the more often it will be replaced.

If this customer had replaced his filters in a timely manner, he may have saved that compressor. Yes, an animal in your ductwork can kill a compressor.

A Very Funny Snake In The Ductwork Story

If you scream loud enough, even a snake will freak out. Here’s a personal story that will always be treasured and never forgotten.

We had a little ranch house about ten miles out of Bend, Oregon, in the 70’s. I had just installed a new split system Fraser-Johnston heat pump with an electric furnace and duct system in the crawl space.

I was startled by my wife screaming from the bathroom. I ran to the door and it was locked. She was screaming “snake”. By the time we got the door unlocked, there she was, standing on the vanity/sink, freaked out of her mind.

And down on the floor, frantically flipping and flopping around the room like a scared rabbit was about a three-foot snake. Turned out to be just a bull snake, but in case you don’t know, they have every characteristic of a rattlesnake, only non-venomous, and they have no rattles.

The incident started when she was sitting on the toilet. When she looked down, only a couple of feet away, there with it’s head sticking out of the heat vent was this snake.

She screamed, and I bet if snakes could scream, that bull snake would have screamed too. How he got his body through that register, I can only imagine. They can go through some tight spots. Whoever wrote this article titled Can Animals Get Into My HVAC System? feels the same way.

When I investigated the situation, I found a small section of duct that wasn’t sealed properly to the air handler under the house. Check our guide on proper duct sealing to prevent surprises like this. Where we live now, I’ve dealt with several rattlesnakes.

Just kidding about screaming to eradicate a snake. It could work, but I only have one incident and one snake to tell about. A real rattler would probably react differently. He would likely coil and strike.

When Should You Call a Professional?

If you discover or suspect an animal in your ductwork, it can be tempting to handle it yourself. While some minor inspections and traps might be manageable as a DIY project, there are times when it’s safer — and smarter — to call a professional.

• – You smell a strong, persistent odor (a sign of a dead animal).
• – You hear loud scratching, banging, or aggressive noises.
• – You can’t safely access attic or crawl space duct areas.
• – You suspect multiple animals or nests.
• – You see major duct damage or pulled-down insulation.

In these situations, a wildlife removal specialist or professional exterminator can safely remove the animal, sanitize affected areas, and help prevent future intrusions. Calling a professional can also save you time, protect your HVAC system from costly damage, and keep your home safe and healthy. When in doubt, it’s always better to get expert help than risk further damage or health hazards.

Conclusion

• Encourage prevention
• Recommend regular maintenance
• Suggest professional help if needed

The perimeter of your home is there to keep out the bad weather and intruders, whether they are human or an animal in your air duct. Great care needs to be taken to keep up this barrier.

I had an instance once where pack rats actually climbed the siding of my cabin and chewed through the screen vent into the attic. Another time a rat got in through an open door on one of those hot summer nights. He made a home behind the kitchen cupboards.

My customer with the cat problem is such a loving guy. He has a number of farrow cats. He’s captured most of the adult cats and had them fixed. The humane society refuses to take them. He feels stuck.

His handyman has supposedly plugged the holes into the attic, but in the crawl space he’s afraid to block off the warmth they need for the winter. I’m working with him to find some homes for them.

So, carefully scrutinize the exterior of your home. Properly block, plug or fix any possible access to attics and crawl spaces. Decide what is most important. A healthy secure home, or intruders that will destroy your investment.

I hope you don’t have to call an professional saying, “I have an animal in my air duct”.