How do you change an opel astra fanbelt?

To change the fan belt on an Opel Astra, first ensure the engine is off and cool. Locate the belt routing diagram, usually found on a sticker in the engine bay. Loosen the tensioner pulley using a wrench, then remove the old belt from the pulleys. Finally, install the new belt according to the routing diagram and re-tighten the tensioner before starting the engine to check for proper alignment.