One day you notice a strong smell from your car that was not there before. Maybe it is a sickly sweet smell or a bad odor like sulfur or vinegar. Closer inspection shows that the smell is coming from the air conditioning vents. So why do air conditioners have odd chemical smells?
Chemical smells in car air conditioners can be due to coolant leaks, mold, wiring issues, or other external sources of smells. Fixing these issues might require the replacement of air conditioning components or thorough cleaning of the air conditioning system.
We’ll look at the common causes of chemical smells in cars and identify what process is making the odor. Then we’ll look at some troubleshooting ideas to help remove or minimize the smell as well as signs that you need your vehicle to be looked at by an expert.
Why Does My Car Air Conditioner Let Out A Sweet Smell?
A sweet or ether-like scent could be a sign of leaking refrigerant. These special chemicals are used by your car air conditioner to cool or heat air. It is a potent chemical that should not be exposed to humans
When the system is working, the refrigerant travels through closed vents and hoses. But due to wear and tear, leaks can develop. If the leak is large enough, you can smell the refrigerant particularly if it is pooling in the airways.
If you notice the air conditioner is not working as effectively it may have a coolant leak. If you hear a bubbling or hissing noise coming from the system this is another sign of failure.
Ethylene glycol is the main component in coolant fluid that makes it best suited to lowering the freezing temperature of a liquid. It’s also the same substance that gives the fluid its strangely sweet scent.
You can try comparing the smells of your car’s air conditioner and the spare coolant you have and see if it’s the same. If the smell is the same you almost certainly have a coolant leak somewhere.
Why Does My Car Air Conditioner Smell Like Mold?
A musty or acidic scent could be a sign of mold in the system. Over time, the system creates a lot of moisture via the cooling and heating process that may sit in the vents. That moisture can lead to mold or mildew growth.
Sometimes this can come across as a pungent vinegar smell when first turning on your air conditioner. Unfortunately, these types of issues are hard to fix yourself as the mold can be deep in the system.
The metabolic byproduct of mold and mildew called “mycotoxins” is responsible for the stench. Generally, you will need an expert to check coils and ducts.
Why Is There A Bad Smell When I Turn The Cool Air On?
Other sources of bad smells can be internal or external to the vehicle.
External issues can be nearby open containers of chemicals near the air intake. If you have something in your garage near the vehicle, when you turn it on you are sucking in these chemical smells. Check for open containers sitting near the intake and close or move them to another area.
The vehicle’s cabin air filter does a good job of filtering out dust, debris, and other harmful materials. However, it’s not quite strong enough to filter out very strong smells like gas. This means that if your vehicle is leaking gas, there’s a good chance that the smell of gas will get sucked into your cabin through the air conditioning.
Less common but still possible is a sulfur smell. This is from leaking battery acid and the smell can seep into the air conditioning system.
The smell of burning rubber could be due to the compressor. The compressor has the main job of circulating refrigerant and is in effect handling the cooling process of your air conditioning. The unit can have issues like mechanical failures which will tend to smell like burning rubber.
Electrical systems like an air conditioner are prone to all sorts of issues. These include shorts, faulty wires or battery issues. A burning plastic smell is likely to indicate that the problem lies somewhere in the electrical systems.
Finally, oil can leak from your engine through the various hoses and pipes. If oil splashes onto the hot engine or other hot parts under the hood, it can quickly emit a burning oil odor that can be blown into the cabin.
How Can I Clean My Car Air Conditioner?
You should aim to clean your car’s air conditioning every six months.
Leave the engine running while parked and the heat turned up high. Make sure the air conditioning is off. Leave windows and doors closed for about five minutes. This process will help reduce moisture in the vents.
Automotive stores sell specialty air conditioning cleaning products. These are referred to as decontaminating products for bacterial, fungal, and mite infestations. The instructions should be followed but the general process is you spray the material with the air conditioning on.
Heavy use of air conditioning can degrade the quality of the air quality and odor. Flushing the coolant used by the air conditioning system will remove nasty buildup and likely also increase the effectiveness of the system.
Aerosol air conditioning flush is a great product to use to flush out the old refrigerant. This can be done easily via the dashboard or glove box.
Any leaks or holes on tubing or ducting can be sealed. This will prevent odors from leaking in or out. However, this may not work long term and it may be better to just get the part replaced.
General cleaning out of debris and junk that has accumulated in the air conditioning system may be enough to get rid of bad smells. The system has many filters which can catch and hold material that emits a bad smell.