Clicking sound at idle from engine bay?
 

I feel like this may have been discussed before but there are so many threads about clicks from various parts of the car I figured I might as well make a new one specifically about the engine bay @ idle. Does anyone else have an intermittent sound at idle every ~15 seconds? The sound will go off and you can hear the engine sounding slightly different after the click before it clicks again in about 15 or so seconds and again changing sounds slightly. I believe the RPM might move ever so slightly too when this happens. This is at idle so I assume it wouldn't be a transmission or differential sound. It is pretty worriesome.

Might be worth noting that AC is on usually (I am not sure whether it happens when AC is off, will check when I can).

It is most likely your A/C compressor clutch kicking on and off. That is perfectly normal.

Yeah it was the AC, thanks for input. Now can I can breathe a sigh of relief my DI injectors aren't exploding. =p