Causes Of Bad Smell From Car A/C & How To Fix It

If you’re detecting a bad smell from the car A/C, there are a number of things that can cause it. Many drivers describe the scent as resembling gas, dirty socks, rotten eggs, or burnt plastic. This should be a warning that something is wrong and you’ll definitely need to identify the source.

What Causes The Awful A/C Smell?

To understand where the smell comes from, you must first understand the basics of air conditioning. Technically, your vehicle’s A/C doesn’t produce cold air. Rather, it extracts heat and moisture from the external air, which causes the air within the cabin to become colder. The coils within the A/C unit will condense the moisture and heated air, eliminating humidity prior to transferring the cold air into the vehicle’s cabin from the vents.

Because this airflow is substantially colder than the air that surrounds it, the airflow which enters your A/C unit can produce moisture that will encapsulate its condensing parts. This in turn produces a little stream of liquid that drips out the vehicle via its drain pipe. At least, this is how it’s supposed to work. In reality, the moisture might sometimes fail to leave the automobile, either by drainage or evaporator, and will instead drip onto the air conditioning unit which surrounds the coil. This moisture will eventually begin to produce an odor.

Gas Leakage

If you notice that the vehicle has a gas-like scent every time the A/C is turned on, it is likely that a gas leak is present within the air conditioning. At the moment the A/C is activated, the gaseous scent will transpose within the unit, meaning that the system will take on a fresh and gaseous scent simultaneously. You’ll need to contact a mechanic to help you find the sources of the leakage if you lack the knowledge and tools to find it yourself.

Mold or Bacteria

One of the most common reasons why A/C systems start to smell bad is because of the presence of mold or bacteria. Both are microorganisms that have their place in nature, but certainly not in your car’s air conditioning system. They will usually accumulate near the evaporator which is often situated near the rear of the dashboard panel. If the bacteria or mold is not removed the stench will worsen over time and might even lead to respiratory problems, especially in those that already have asthma or allergies.

Coolant Leak

If you’ve got a coolant leak, your vehicle will often smell sweet. While the scent is certainly better than that which is emitted from mold or bacteria, it is still a cause for concern. The first thing you’ll want to do is inspect the cooling system because the sweetened smell most likely comes from either antifreeze liquid or ethylene glycol. The source of the leak might be the radiator but it could also be the heater core, coolant housing, or pipes.

The best way to eliminate the bad smell is by cleaning your A/C system. There are antifungal and antibacterial products on the market that can do it, and if they don’t work, you’ll want to have the vehicle inspected by a mechanic.