Where can I find the air conditioning low pressure port on a peugeot 206?

I need to locate the low pressure port on my air con system in a 1999 peugeot 206 but am not sure where it is. I've looked for diagrams but cant find anything. HELP!!|||your low pressure valve should be located on your compressor which will be run by a belt from your engine. also have the system checked by a competant air con service.