You may not notice your car's air conditioner much at all, as long as it keeps your car comfortably cool. Your unit can, however, sometimes develop problems that aren't always easy to diagnose. For example, it's not uncommon for drivers to suddenly start noticing a bad smell in their cars when air conditioning is running. What's the problem?
The Air Filter
Car air conditioning units usually run air through a cabin filter. These filters take out stuff you don't want in the air in your car, like pollen and dust. They don't, however, last forever. If they're doing their job but aren't replaced regularly, they get clogged up with the debris they filter out. This can start to smell, especially if the filter is also exposed to moisture.
Bacteria
Bacteria can be found anywhere in an automotive air con system where there is moisture. If conditions are right, you could be smelling mould, mildew or a fungus. As well as being pretty unpleasant, it's not good for your health to breathe in these kinds of bacteria, so this is a problem that needs sorting, especially if you drive a lot.
Dust
If your car smells dusty rather than rank, then your air conditioner may have a build-up of dust in areas that aren't dealt with by the cabin air filter. Dust can also ultimately lead to a worse smell. If it gets wet, then bacteria may set up home on it.
Blockages
In some cases, you get a nasty smell from your air conditioning if there is a blockage in the system somewhere. For example, your system's evaporator is there to take moisture out of the air that is pumped into your car. It drains this moisture out of the car via a tube. If your evaporator or its tube gets blocked by dirt or dust, then it may not be able to drain all the water out. This residual water gets smelly if it sits there for long enough.
While you can try to fix a bad smell yourself by cleaning out your vents or using home air conditioning treatments, this will probably only give you a short-term solution. Plus, you risk damaging your air conditioner if you don't know what you are doing.
Automotive air conditioner repair technicians can take a look at your system and diagnose the problem. They can change air filters, deal with blockages and give your air con a full antibacterial clean to get your air smelling fresh and sweet again.
