It has been hot lately so I have been using my AC. Every now and then after I stop driving after the ac has been on the clutch makes this clicking noise when I put the clutch in. 2000 a4 1.8t. any help would be great thanks.

 

Are you trying to say that having the AC on might be affecting your clutch for the transmission?? Probably not. There is a clutch in the AC compressor, then there is a clutch for your tranny, im having a hard time understanding what you are trying to say. But if you hear a clicking noise from the clutch pedal when you press it, it might be the spring that helps the pedal return upright. Im not even sure if there is a spring, but I had the same problem in my old rx7 and that was the cause. Try to be a little more descriptive.

 

There was a mechanical clunk/clicking when i pressed the clutch once, the slave cilinder had died. w00t.

 

From the crappy description it sounds like your throwout bearing is going out. If it happens when you depress the clutch pedal about half way its the throwout bearing, if it does it when the clutch is fully depressed its the pilot bearing inside the flywheel thats going.