I noticed today that when I turn on my AC it makes a "clink" sound and then when I turn it off it makes a "knock" sound. Is this common with 97 Maximas? Is this an indicator of something going bad?

 

Did you never notice that before. I can audibly hear the air come on and off on all cars I have ever been in with air equipped. Its the fan kicking on and shutting off....normal, unless its has been growing noticeably louder and you think you need ear pugs.

 

It's not the fans turning on and off. It's the compressor's electromagnetic clutch engaging and disengaging.