when i press the switch on the dash to alter the air from outside fresh air to recirculated air the flap just makes a thump every few seconds,any ideas ? is it easy to get at ?
That sounds like a servo-operated flap with a worn actuator.
In many cars those components aren't easy or quick to get at, but a glance at a Haynes manual for your model will tell you how well the task is documented and how long it would take you.