Nissan Repair: high idle and a/c compressor, vacuum leaks, air control valve

Question
I have a 2000 xterra 3.3v-6.It starts fine, but now idles on about 1500 rpm cold or hot.Also the a/c compressor runs all the time,its not climate controlled.I unplugged the pressure switch but it still runs.I had to unplug the compressor to shut it off. Any help will be appreciated.Thank you for your time.

Answer
Michael,

First, the idle air control valve is probably stuck and needs to be replaced.  If not, you have one heck of a vacuum leak that is causing the vehicle to run fast.  First, check for vacuum leaks like around the throttle body to the air meter (air filter box).  And, check for any other vacuum leaks like hoses and such.

Second, the airconditioner is commanded by the interior control panel.  If you have it on defrost in the winter the compressor will come on.  If it stays on, even with the controls off means that the compressor relay is stuck and needs to be replaced.  The pressure switch would not disengage the compressor if the compressor relay is stuck on...