Picasso Pressostat, where?

[PicassoPigeon]

Trying to find the damn pressostat on my 52 reg picasso 2.0hdi. Want to bridge the connections to see if its at fault for my aircon failing to work. Have so far had the fan running by bridging the 3 fan relays on top of rad, but can't find the pressostat. Had a look through front grill and can find what i believe to be the fan resistor connector?

Any help? Thank you.