thats the thingy hoosit
if your referring to the little one in the foreground of the pic I think thats an idle up solendoid to increase the revs when the aircon is on, mine had one but it didnt work, though come to think of it it could be an idle switch as well, never really look ed to hard at it
the vacuum cannister thingy behind it is also an idle up, this time for electrical load, if the lights, heater fan or rear demist are on it increses the idle so the battery doesnt go flat