Appear to be identical to Pug306, goto this link
http://www.peugeotlogic.com/workshop/base/workshop.htm
and then electrical (top right) then 306cooling fans on left.
They also point out a common fault on a/c control unit ( dry
joint on a/c control unit ) see a/c compressor not working section.
Q: where would I find the a/c control unit on a Xantia, presumably not far from the slider control.
Pete