The Saab 900S uses a single drive belt to transfer rotational energy from the crankshaft to the engine accessory components, including the alternator, air conditioner and power steering. This makes it easier to replace the belts that control the accessories, as you only need to contend with one idler pulley. However, if you do not have a diagram for how to route the belt onto the pulleys, make one before starting. This makes the task of putting the drive belt back on much easier.
Locate the idler pulley mounted to the engine block, between the alternator and air condition compressor. The pulley has a square hole in the centre of it.
Place the ratchet into the square hole on the idler pulley, and lift up on the handle. Slide the belt off the idler pulley, and lower the ratchet handle.
Remove the drive belt from the rest of the pulleys, and place the new belt onto the Saab pulley system. Do not place it on the idler pulley.
Pull up on the ratchet handle, and slide the belt over the idler pulley.
Lower the ratchet handle to apply pressure to the bet drive, and remove the ratchet from the idler pulley.