Remove the air quality sensor cover. 3 4 5 Clean the air quality sensor, the dust inlet and the dust outlet with a lightly moistened cotton swab. Dry them with a dry cotton swab. Reattach the air quality sensor cover. English 17 Filter replacement Filter maintenance When one of the filters is almost full and has to be cleaned or replaced, the corresponding light or lights (the pre-filter cleaning light or one of the filter replacement lights together with the ‘REPLACE FILTER’ light) star t to flash.You then have to clean or replace this filter. This air purifier is also equipped with the Healthy air protect lock to ensure that the filters are in optimal condition when the appliance is operating. When you do not replace filter 2 (AC4004 only), filter 3 and/or filter 4, the appliance stops operating and the appliance is locked. When the appliance is locked, the filter replacement light of the filter concerned and the ’REPLACE FILTER’ light light up continuously. Filter cleaning light and filter replacement lights The filter cleaning light and the filter replacement lights indicate which filter has to be cleaned or replaced. -Filter cleaning light 1 flashes: you have to clean filter 1 (pre-filter). See chapter ‘Cleaning’ for fur ther instructions. -Filter replacement light 2 and the ‘REPLACE FILTER’ light flash: filter 2 (multi-care filter, AC4004 only) has to be replaced. -Filter replacement light 3/4 and the ‘REPLACE FILTER’ light flash: filter 3 (activated carbon filter) and filter 4 (HEPA filter) have to be replaced. Note: Filter 3 (activated carbon filter) and filter 4 (HEPA filter) have a similar lifetime.Therefore they have to be replaced at the same time. Filter replacement lock If you do not replace a filter in time, the appliance stops operating approx. 2 weeks after the filter replacement light star ted flashing. When the appliance is locked, it does not operate until you have replaced the full filter and pressed the reset button. Note: The time between the filter replacement signal and the locking of the appliance varies, depending on how often you use the appliance. Note: When the power on/off light, filter replacement light 2 or 3/4 and the ‘REPLACE FILTER’ light are on continuously, the appliance is locked (see section ‘Filter maintenance’ in this chapter for more information). and holding the on/off button. cleaning light and filter replacement lights’ above). filters and resetting the appliance’ below). Replacing the filters and resetting the appliance Tip: Place the appliance against a wall for more stability when you remove or insert filters. 1 Switch off the appliance and unplug it. 2 Place your fingers in the recesses of the side panels and gently pull the bottom part of the front panel towards you. Then lift the hooks at the top of the panel out of the top of the appliance. 3 To remove filter 1 (pre-filter), grab the two projections and pull the filter towards you. 4 AC4004 only: remove filter 2 (multi-care filter) from the back of the pre-filter. 1 2 18 English Filter replacement lock If you do not replace the filter in time, the appliance stops operating approx. 2 weeks after the filter replacement light started flashing.When the appliance is locked, it does not operate until you have replaced the full filter and pressed the reset button. Note: When filter replacement lights 2 or 3/4 and REPLACE FILTER on the control panel are on continuously, the appliance is locked (see section ‘Filter maintenance’ in this chapter for more information). How long it takes before the appliance is locked depends on the operating time and speed level selected after the filter replacement alert. Approximately 1 day before the appliance locks, it beeps every 30 minutes to inform you that one of the filters needs to be replaced. When the appliance is locked, you hear a beep when you press any button. You can switch off the appliance by pressing the on/off button. If the appliance is locked: 1 Check which filter needs to be replaced (see section ‘Filter replacement alerts’). 2 Switch off the appliance and unplug it. 3 Replace the appropriate filter (see section ‘Replacing the filters’). AC4072-4074_um_120424.indd 19 24/04/2012 15:47:36 5 To remove filter 3 (activated carbon filter), grab its tag and pull it towards you. 6 To remove filter 4 (HEPA filter), grab its tag and pull it towards you. 7 Discard the filter that has to be replaced and unpack the new filter. 8 Put filter 4 (HEPA filter) back into the appliance. Note: Make sure that the side with the tag points towards you. 9 Put filter 3 (activated carbon filter) back into the appliance. 10 AC4004 only: reattach filter 2 (multi-care filter) to the back of filter 1 (pre-filter). Note: Make sure that the front of the multi-care filter points towards the prefilter. English 19 11 Put filter 1 (pre-filter) back into the appliance. Note: Make sure that the side with the two projections points towards you. Note: Make sure that all hooks are properly attached to...