What is the psi for ac on 2000 Ford Focus?

There isn't a single PSI value for the AC system on a 2000 Ford Focus (or any car for that matter). The pressure in the AC system varies depending on the ambient temperature and whether the compressor is running. You'll need to consult your owner's manual for the proper pressure ranges, which will specify low-side and high-side pressure charts based on temperature. These charts will guide you in diagnosing potential AC problems. Improperly charging the system can damage the compressor.