A/C Noise when turning on A/C

[mshw777]

I have a 2003 Xterra 4 cylinder. I've noticed when I engage the a/c, the compressor makes a "clunking" noise. Even while I'm driving and the a/c is running, when the compressor re-engages, it continues with variations of "clunking" noises. Under factory warranty, I've already had Bankston Nissan replace the a/c compressor; but to no avail...same noise but this time with a very apparent "hissing" sound when turning on the a/c. Does anyone else have the same experience, or any suggestions??? I'm still under warranty, so taking it back a 2nd time is not out of the question....

Thanks for replies.

[OffroadX]

The "clunking" is normal, my V6 does it too.

[chubbybubba1]

The clunking sound is the clutch on the a/c copressor. Totally normal. The hissing sound is common also in any ac system. You have no problems.