Bad smell coming from your car's AC? Here's how to fix it

If the air conditioning in your car smells unpleasant, this may indicate that mould has formed in the cabin filter.

The filter is responsible for removing pollutants, dirt and pollen from the air but over time it can become clogged and less efficient.

Germany's Auto Club Europa (ACE) recommends changing the filter once a year. It's possible to change it yourself but, depending on the model, it may be difficult.

Sometimes the filter is located under the hood, in other cases you can get to it from the inside. It may be necessary to remove other parts first. So it's best to take the car to a workshop if the job is too complicated.

The ACE recommends installing a filter containing activated carbon as these also filter out a lot of harmful exhaust gases and odours from the air.

Bacteria and mould can cause unpleasant odours in the air conditioning so ideally the system should be disinfected annually. Special products to do this are available if you want to do it yourself, otherwise go to a professional.

The ACE recommends having the air conditioning system inspected by experts at least every two to three years. It's also important that the amount of coolant in the system is checked regularly as around 10% of it is lost every year. Topping up is definitely a job for professionals.

Leave the fan running for a few minutes after switching off the air conditioning to reduce the condensation remaining in the air ducts - moisture is a perfect breeding ground for bacteria.

But what if you've put in a new filter and disinfected the air conditioning and the car still smells? Having an ozone treatment done by a car repair shop can be a solution. The process involves sending ozone inside your car using a special generator to kill germs and mould spores and eliminate bad smells.