Sort of like an old gym bag, this smell results from dust and bacteria build-up in the AC ductwork caused by a dirty cabin filter. This is the leading cause of bad AC smells. Replacing the cabin air filter is a quick, inexpensive fix any DIYer can do. Check your owner's manual for detailed instructions.
That musty/damp/mildrew smell you may notice from the vents is generally caused by one, or both, of two things. 1) Running your A/C on recirculate almost always. 2) Failing to dry out the evaporator when using the A/C (this is the most common reason).
The rotten eggs smell usually comes from the catalytic converters, this happens when the vehicle runs rich and the fuel has contact with the catalytic converter internal. You may have a clogged catalytic converter, that would explain the smell and the sputtering.
Contamination. Not all dead animal smells in your house are actually from dead animals. Over time, contaminants such as dust, debris, and mold spores can build up within the air ducts.
Although rare, there are instances where animals can get inside your vehicle and die. Dead animals can get stuck in the air ducts and give off a nasty smell as they decompose.
What does a dead mouse smell like? The smelly carcass is emitting a pungent odour of decay and a “bouquet” of toxic gases like foul-smelling of rotten cabbage thiols, methane, hydrogen sulphide, ammonia and pyruvic acid.
If you get the smell of a rotting dead animal, take your car to the garage. Most likely, a rodent or other animal has died after entering the engine compartment or the HVAC system. The problem is more common if your vehicle is rarely used.
Failing Catalytic Converter (Sulfur Smell)
Over time, the catalytic converter can become overheated, contaminated with gasoline in the exhaust or simply wear out. When this happens, you're likely to notice a rotten egg, sulphurous smell coming from the exhaust.
One potential reason your air conditioning in car smells bad is due to a build-up of dust and dirt on the air filters. This can prevent air from flowing properly throughout the system, keeping moisture trapped. Most manufacturers recommend replacing a car's air filters every 15,000-30,000 miles.
The mouse in inside the heater fan motor's fan blade (it looks like a hamster wheel). Have your mechanic remove the bolts that holds the fan motor to the duct under the dash. Once the motor is out, the rodent should be visible. Clean the blower motor with disinfectant and then have the foam process done.
Here's How to Handle a Dead Animal in Your Vent
You should explain the situation when you call for service; some HVAC service providers may refer you to an animal control provider instead, but many HVAC technicians will be able to remove the dead mouse or rodent properly.
If your AC unit smells like something crawled in there and died, then that may be exactly what happened. Rats and mice often end up trapped inside air conditioners, and rodents don't smell pleasant when they pass away.
Sort of like an old gym bag, this smell results from dust and bacteria build-up in the AC ductwork caused by a dirty cabin filter. This is the leading cause of bad AC smells. Replacing the cabin air filter is a quick, inexpensive fix any DIYer can do. Check your owner's manual for detailed instructions.
This usually takes several weeks, although the smell will lessen gradually over that time. Here are some suggestions to get through this tough time. Keep the windows open as much as possible to air out the interior.
A Bad Catalytic Converter Can Burn Through Overtime
Most of the problems related to catalytic converters do not affect the function of your vehicle. If you have to deal with a fully plugged catalytic, avoid driving your car. If you notice smog coming from your car, it is best to seek professional help immediately.
Catalytic converters have a broad range from about $900 on the low end to $3,500 or even a bit more on the high-end. The difference in price is primarily around parts, because labor is a relatively small part of the cost.
Cars are designed with a variety of electrical elements, including the battery and alternator. If your car smells like burning electrical or like it's burning under the hood, this could be the cause. If the check engine light comes on while it smells like burning, the spark plugs could be the problem.
Air conditioners that smell like rotten eggs are caused by dead animals caught within the unit. Distinct and unmistakable, this odor will be sent throughout your entire home as soon as you turn the unit on. Additionally, animals could also nest in ductwork, getting trapped and possibly damaging the system.
The smell of a dead rat can be harmful to a person's health due to the toxic gases and microscopic compounds of the dead animal that are constantly being released into the indoor air. Since most homes are not consistently ventilated, the gases permeate into the respiratory tract and can potentially cause illness.
The decomposing smell will circulate throughout your entire home as long as the system is running. If the dead animal is a rat, you'll also likely notice yellow stains seeping through the ceilings or around the vent — the trail left behind when they urinated.
Finding the exact location of the deceased rodent is crucial for resolving the issue. Begin by thoroughly inspecting the interior of your car, paying attention to small spaces and crevices where rodents may hide. Common areas to check include the engine compartment, trunk, and interior gaps.
Even if you can't locate the dead mouse, the smell will eventually dissipate with time. Still, it's important to find the animal for sanitary reasons. In the meantime, you'll want to do something about the smell.