How Often Should You Clean Your Car's A/C? (And How To Do It)

With the arrival of summer comes increasing temperatures, and that means keeping your car cool becomes more important than ever. There are some cheap ways to do it, but the most effective way is to make sure that your car's A/C is in good working order. To function as intended, your A/C will need to be kept clean and have the correct amount of refrigerant. If it doesn't have enough refrigerant, it will need recharging. There are several telltale signs to work out when it might need recharging, including reduced airflow, unpleasant odors, or hot air blowing into the cabin even when the A/C is set to blow cold.

Keeping the A/C system clean is just as important as having enough refrigerant, and one of the easiest ways to help keep it clean is to regularly change the cabin air filter. This filter is responsible for trapping dust, debris, and particles from the outside air and stopping them from being blown into the cabin, but over time, it will become clogged. How quickly it will clog depends on where you live, how often you drive the car, and the quality of the filter itself, but your car's owner's manual should have recommendations on when it needs changing. A rough estimate is that it will need changing at least every 30,000 miles, but some cars will need to have it changed more frequently.

Changing a car's cabin air filter isn't usually a difficult task. Many cars have their cabin air filters behind the glove box, although the exact location can vary between models. You might need a screwdriver or a wrench to open the filter box, and then the filter can be pulled out for inspection. If it's visibly dirty, it will need replacing. New cabin air filters can be bought from auto parts stores. If you're not comfortable doing it yourself, it should be an easy job for a mechanic, and some auto parts stores may also offer to fit air filters when you buy them.

Many auto parts stores will also offer A/C system cleaning spray, which is designed to clean bacteria and mold from the inside of the car's system, including the evaporator. The cleaning sprays will come with a flexible tube attached to the top of the spray can, which can be directed into the A/C system's air vents to clean them.

Before starting, you'll need to remove the cabin air filter and check that the condensation openings aren't blocked. Follow the instructions on the spray to ensure that the cleaning solution is properly distributed into the system, then leave it to take effect. Liqui-Moly's spray requires a 15-20 minute wait, but be sure to follow the recommendations of your chosen brand of cleaner. Then, run the fans for a further 10 minutes to dry out the evaporator surface.

There's no set time frame for when to clean the vents using spray, since different driving conditions and the frequency of A/C system use will determine how quickly mold and bacteria build up inside the vents. A persistent moldy smell can be a sign that the system needs cleaning, but before you head to a parts store, it's worth running the heater on its highest setting for a few minutes to dry out the system. Sometimes, that's enough to clear the moldy smell on its own. The smell can also be a sign of a failing A/C compressor, which will require a trip to the shop.

Using a store-bought A/C cleaner is the cheapest way to keep the system clean, but it's worth taking it to a shop if you aren't confident with the DIY option. A shop should also be able to give the system a more thorough clean using highly pressurized air if it's needed. They'll also be able to diagnose whether there are any further issues with the A/C system, such as whether a component like the compressor needs replacing.