Most likely cause is the freezer evaporator is frozen up due to a faulty thermistor. They call it a NO FROST PROBE. Available to buy here: http://www.interspares.co.uk/product-info.php?cPath=2192_64_2399&products_id=155771&osCsid=941112d554d061afaac9ea0593fe7603
Hope this helps.
Interspares Technical
February 2009
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