The air conditioner works, but there is almost no air: A small filter that drivers often forget

When the air conditioning in your car fails in the middle of the August heat, many drivers immediately think that the refrigerant has run out or the compressor has failed. However, if the fan is running but there is little air coming out of the vents, a musty smell is present, or the windows are slowly defrosting, the cause could be much simpler: a clogged cabin or pollen filter.

This filter is located in the ventilation system and traps dust, pollen, particles and some other impurities before the air enters the cabin. Depending on the model, it may be located behind the glove compartment in front of the passenger compartment, under the dashboard or at the bottom of the windshield. When it becomes clogged with dirt, the fan has a harder time pushing air, so the air conditioning works less well, even though the cooling circuit may be working properly.

The most common signs are reduced or uneven airflow, unpleasant odors from the air vents, noisier fan operation, and slow defogging. An activated carbon filter can also help reduce odors and some gaseous pollutants, but it doesn't last forever. Driving on dusty roads, frequent city traffic, and pollen season can shorten the replacement interval.

RAC As a guideline, it states up to about 24.000 kilometers, or at least once every 18 months, but the service manual for the specific car takes precedence. In our country, where dust, high temperatures and driving along the coast or construction sites are not uncommon, an inspection may be needed earlier. Replacement is simple on some models, while others require removing the lining, so there is no need to force the plastic clips.

It is important to distinguish the filter from other faults. If the air flow remains strong, but the air is not cold, the problem may be insufficient refrigerant gas, a leak, a condenser fan, a sensor or a compressor. Refilling gas should not be done blindly: a serious service first checks the pressure and tightness of the system, because gas does not "disappear" for no reason. Air conditioning service is also usually not part of a standard minor service, so it should be asked for separately.

Even a new filter will not always eliminate the odor. If moisture and microorganisms remain on the evaporator, professional cleaning and disinfection of the ventilation system may be necessary. A sweet smell, a greasy film on the glass, or a damp carpet can also indicate a coolant or condensate drain leak, which requires a mechanic's inspection.

Before a driver pays for a major repair, it's worth seeking clear answers to four questions: what is the airflow like, when was the filter last changed, has the system been tested for leaks, and what exactly is included in the service offered. Sometimes the solution to a "poor air conditioner" is a small consumable, but good diagnostics are what separates a cheap repair from an unnecessary expense.

Article prepared with the support of AI tools.