Why A Car Smells Like Pee & How To Fix It

Has your vehicle’s air conditioning (AC) system began to spew a terrible urine odor into the cab through the vents?

The urine odor is most likely caused by a build-up of mold, mildew, and bacteria on your vehicle’s AC evaporator, or, to be more precise, the mold’s mycotoxins. Mycotoxins produce ammonium, which also happens to be present in urine, and this is what you’re smelling.

The fragrance is sometimes less visible after the AC has operated for a while and the system has cooled down.

Why Does Your Car’s AC Smell Like Pee?

The evaporator is an integral component of a car’s air conditioning system. The purpose of the evaporator is to remove any moisture from the cooled air. This moisture should disperse or drain into the earth through the drain hole. Mold will grow if the drain hole is closed or if the moisture does not completely evaporate.

Fortunately, the problem is usually relatively simple and inexpensive to remedy, so you won’t need to take it to a technician.

Mycotoxins, or byproducts, are produced when mold is collected, and they are sometimes more harmful than the mold itself.

Dangers of Mycotoxins

Mycotoxins are secondary metabolites generated by microfungi that can infect humans and other animals, causing sickness and death. Some mycotoxins and mycotoxin derivatives have been used as antibiotics, growth promoters, and other types of medications due to their pharmacological properties, while others have been implicated as chemical warfare weapons.

How To Fix The Problem

If you suspect mold as the source of the odor, there are a few options for resolving the issue and getting your vehicle smelling like new again.

The Least Likely Reason Your Vehicle’s AC Smells Like Pee

Why A Car Smells Like Pee & How To Fix It

Small animals, particularly mice, will nest in the air intake system of a car. Mice excrement and urine might accumulate.

Before cleaning the intake, you must disassemble it and clean it by hand. Wear gloves and a mask if you’re going to go outside! … Or, better yet, hire someone who knows what they’re doing!


You have the right to be comfortable in your own home, and an air conditioner that stinks isn’t one of them. The simplest way to avoid dirty sock syndrome is to change your air filter on a regular basis and arrange yearly air conditioning repair. We’ll make sure the evaporator coil is clean and the drainage system is clear, since stagnant water might cause smells.


Typically, mold and mildew will have a pee-like smell when they grow inside of a car’s AC and indicate there may be moisture built-up in your air conditioner’s evaporator. A strong pee smell could also mean that bacteria is growing inside your vehicle’s AC, so try to have your car inspected as soon as possible.
If you put equal parts water and vinegar in a spray bottle and spray the inside of your car (not too much, of course), it should help reduce or remove the odor.
Air Conditioner Smells Like Cat Pee. A powerful ammonia odor means there could be mold flourishing in your air conditioner or ductwork. The smell isn’t the mold itself, but the mycotoxins that mold creates.
Leaks in your ductwork can allow dust and mold spores to get inside and grow there. As a result, you might detect a musty or ammonia-like smell when your AC kicks on. The solution: Contact an HVAC technician. They can clean out and seal your ductwork to prevent the mold from growing back.
Latest posts by Spring Bamboo (see all)

Related Posts

Leave a Reply

Your email address will not be published.