Blocked vent pipe - pipe that outputs the steam outdoors? If it has no pipe -its a condenser drier.
Washer Dryers work by having cold water trickle down the inside of the drum whilst hot air is being blown into it.The hot moist air from the washing converts back into liquid when it hits the cold water, and it is pumped out along with any fluff that may be with it. Unfortunately the internal ducts and channels get congested because of this fluff and prevent the cycle being completed. The condenser needs to be removed and cleaned out thoroughly and so does the sump and outlet hose. Check the water receiver tray.
Repair and service your own washing machine. Go to www.2ndwave.co.uk/manual.html
dannyboy
December 2008