A TIDY JOB
During only one hour driving, an air volume of up to 200,000 litres is blown into the vehicle interior. All the more important is the regular replacement of the cabin air filters. The MAHLE filter experts recommend: replace filters after every 15,000 km or at least once per year. If the cabin air filter is clogged up or fails completely, the pollutant concentration in the interior of the vehicle can increase up to six times of that of the outside air. MAHLE cabin air filters supply driver and passengers reliably with cleaned air to breathe and safeguard their health, well-being and the driver’s ability to concentrate even in the presence of smog or high pollen count.

HOLDING BACK THE DIRT
Dirt particles such as dust, pollen or soot, harmful exhaust fumes, high ozone concentrations, unpleasant odours and even fine particulate dust: all these are retained by the cabin air filter – provided it is a combi-filter (LAK) that consists of two fleece layers and an active carbon layer, like this one. Due to the sandwich construction of the combi-filter (see also the scanning electron microscope image), two independent functions have been combined in one filter. The gases (mainly hydrocarbons as well as inorganic and harmful gases such as hydrogen sulphide, sulphur dioxide and nitrogen oxides) are here absorbed by the active carbon layer.

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

BAD SMELLS FROM OLD FILTERS
A saturated filter reduces the blower output and therefore delays significantly clearing of steamed up windows. If the filter change is postponed for too long, moisture binds to the accumulated dust: the filter becomes a breeding ground for bacteria and mould, which settle in the ducts of the ventilation and air conditioning system and lead to extremely unpleasant odours and harmful emissions into the vehicle interior. We like to give you therefore some tips for fast and safe filter change.

CLEAN AIR IS ALWAYS IN SEASON
Spring, summer, autumn and winter: the cabin air filter during the course of the year:

Spring may be the main time for changing cabin air filters, but a look at the filter fleece shows: there is always plenty to collect.

Spring		Summer
Autumn		Winter

In spring, for instance, one can recognise pollen, grass seed and relatively coarse dirt particles. These can even lead to clogging on the surface of the pleat bellows – while the pleats further down remain comparatively clean.

In summer, significantly more soot and fine dust can be found in the filter.

In autumn, the situation is similar to that of summer – however, due to the high air humidity, even more dust and other particles are collected more quickly.

Winter: the year reaches its end and so does the air filter. The filter is so dirty that it can no longer fulfil its intended purpose and will have to be replaced.

USEFUL: THE ENCLOSED FITTING INSTRUCTIONS
Depending on the vehicle type, the cabin air filters are located in different areas. To avoid searching for the fitting location, we recommend a look at the CD-ROM “Filter product range”, or in our online filter catalogue at www.mahle-aftermarket.com – or straight inside the packaging for the MAHLE Filter and Knecht cabin air filters. This is where you can find the printed fitting instructions – clear and always available, saving time and money in the workshop. For easy access, a tear-open strip is integrated in the packaging.

THE DIRECTION IS IMPORTANT
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 strip. Also the correct positioning of recesses and fixing projections should be observed.

THIS IS HOW TO FIT A FILTER CORRECTLY – A STEP-BY-STEP INSTRUCTION BY THE EXAMPLE OF THE LA 71/LAK 71
In order to assure correct fitting of the cabin air filter, several things need to be observed during fitting. The MAHLE filter experts have chosen the LA 71 or LAK 71 as graphic example. These cabin air filters are supplied by MAHLE as original equipment and are fitted, for instant, in the DAF CF85 and XF95 from model 01/01 or 09/02 onward.

		The frame of the LA 71 behind the front panel of the DAF CF85/XF95. The flow direction should be observed during fitting (see arrows, which point here in direction vehicle).
		At first, the filter is slid under the two plastic retainers, while the two grip strips (1) point here downwards.
		The filter is then carefully pushed into the frame until the plastic tab clicks into the intended recess. Care should here be taken to avoid damage to the plastic foam seal.
		This is the correct position of the filter: the plastic tabs are engaged correctly, the frame seals perfectly and keeps out particles including fine particulate dust.
		An obvious fitting error: the plastic tab is not at the intended position (1). The result: the frame bends sharply and the pleats deform (2). This bends also the foam seal – and a gap is formed, allowing dirt to enter freely the interior (arrow).