To allow easy access to the fitting instructions, the packaging comes with a handy perforated “zip”.

The majority of newly delivered vehicles in europe are equipped with cabin air filters. In germany alone, this amounts to more than 10,000 newly registered vehicles per day – and the trend is clearly rising. For the workshop, this means the prospect of attractive additional income due to the growing replacement demand that follows – and the know-how when changing and fitting the profitable cleaning devices.

Cabin air filters do a clean job. During only one hour driving, an air volume of up to 100,000 litres is blown into the vehicle interior. All the more important is regular change of filter elements. It is important to observe replacement periods stipulated by the automotive industry. As filter manufacturers, we recommend changing the cabin air filter after 12,000 to 15,000 km – however, at least once per year or more often in case of higher dust concentration.

This is because a saturated filter reduces the blower output and significantly delays clearing of steamed up windows. If the filter change is postponed for too long, the accumulated dirt of an old filter, together with moisture can become a breeding ground for bacteria and mould. These can settle in the ducts of the ventilation and air conditioning system and lead to extremely unpleasant odours and harmful emissions into the vehicle interior. Therefore, we would like to give some advice here for fast and safe filter replacement.

Searched and found
First of all: where is the filter? You can find information about the exact location on the CD-ROM “Filter product range” or in our online filter catalogue at “www.mahle-aftermarket.com” – and conveniently, also on the inside of our new packaging for MAHLE and Knecht cabin air filters. There you can find the printed fitting instructions – clear and always available, which saves time and money in the workshop. For easy access, a tear-open strip is integrated into the packaging.

Sandwich construction under the electron microscope: combi-filter (LAK), consisting of two fleece layers with an active carbon layer in the middle.

Pointing the way: The right way up
One of the most frequent fitting errors is placing the filter the wrong way round. The correct fitting orientation is exactly described in the vehicle specific instructions. In addition, the flow direction of the filter is indicated with small arrows at the side part. Also, the correct positioning of recesses and fixing projections should be observed.

Perfect fit
When fitting the filter it is also important that it is placed exactly into the intended location. Otherwise, a bypass can develop – this is an opening that allows unfiltered air to reach the vehicle interior. Incidentally, did you know that a bypass caused by improper fitting can have the same effect on the air quality in the vehicle as an open side window?

Custom fit in original equipment quality
Filters from MAHLE are fitted as original equipment. Also workshops benefit from such high quality – because our filters for the Aftermarket are manufactured according to the same high standards.

A growing source of income: Cabin air filters with active carbon layers
More and more customers recognise the trend from cabin air filters with simple particulate filters (LA) towards the more beneficial combi-filters with active carbon layers (LAK). Even separate active carbon packages are used in some vehicles. Due to the sandwich construction of the combi-filter (see also the electron microscope image), two independent functions have been combined in one filter. Cabin air filters with active carbon layers retain not only dirt particles such as dust, pollen and soot but also remove gaseous contaminations such as harmful exhaust fumes, high ozone concentrations and unpleasant odours from the air. These gases (mainly hydrocarbons as well as inorganic and harmful gases such as hydrogen sulphide, sulphur dioxide and nitrogen oxides) are absorbed by the active carbon layer.

Cabin air filters with active carbon layers ensure significantly healthier air in the vehicle interior. This provides considerable relief to allergic passengers, people that are sensitive to smells as well as sufferers from respiratory complaints – provided the filters are of good quality and replaced professionally in good time.

	New: also the packaging for the cabin air filters has now been designed in line with the complete filter range – in the typical design of the two brands MAHLE Filter and Knecht.
	The clearly designed fitting instructions – for fast and safe filter change.

It is vital to fit the cabin air filter carefully – here the most important stages, shown by the example of a LA 242.

	For many cabin air filters, a so-called blade location is used. This blade slides into the first pleat during fitting to ensure tight sealing.
	This filter has been destroyed during fitting: the filter was not fitted correctly over the blades. This has caused the pleats to bend and resulted in a large bypass allowing unfiltered air to flow past the filter. The filter effect is therefore largely cancelled out. The distortion of the filter can also be seen clearly and has a detrimental effect on the sealing at the longer side.
	This is how a correctly fitted filter looks: the pleats are aligned straight; the insert fits exactly into the housing.