Hey mate,
If the clicking is comming from the air con vents when you turn your key to "acc" or start up the car its just the vents opening.
Mine does that on start up, goes away, and then if i put the air con on and have it on feet, and then move it to body, it clicks.
Not a real big problem just another thing comming in most skylines.
A mates 33 and another mates 34 all do the same.