Need advise on Ford Contour

[Intergator]

Looking at a 95 model for my son to drive to school. The engine runs fine but when you turn on the ac the engine idles down and seems to run rough and sometimes kills. The ac works fine and puts out cold air. Could the compressor be going out or does the idle need to be adjusted up? Appreciate any help.

 

[Rob47]

My DD 2000 Ford did this very thing about 2 weeks ago. It was a vaccum hose. Listen for a hissing sound.
Rob