I have a new to me 90' 2+2 NA, and I am having an issue with the AC. I have been searching with no luck. This car has the manual type switch. The air blows cold, but when I move the switch to change speeds, the unit cuts off and on quickly and makes a clicking noise. It's like a cut off switch going off and on very quickly. And sometimes when running, just in one speed, I hear a clicking noise from under the dash even though the air may keep running. Sometimes it slows down some, and sometimes clicking in and out, but usually it keeps running and the clicking noise is fast and random. It sounds like an electrical switch of some sort clicking on and off quickly. I'm having a difficult time explaining, but any ideas on what this may be or how to troubleshoot?

Did you fix it ?,
I have a 90 2+2 i'm parting out, al the AC stuff is perfect

LOL - not yet. I just posted a few hours ago. I can't find the answer anywhere so I'm hoping someone sees this who is in the know...

Could either be a control relay of some sort snapping on and off because it's bad or if the blower speed is what you are talking about, then leaves and trash around it. At lower speeds they hang back but at higher they get sucked closer to then touch the squirrel cage and makes noise then.

I found the answer with some help over at Twinturbo.net. Just in case anyone has the same problems, here is the link. I followed this and it did the trick. Good stuff.

http://www.twinturbo.net/nissan/300zx/f ... er-Zs.html