First thing you want to check is if your compressor is ok. Try jumping switch and see if compressor turn on-- just for few seconds. Compressor will kick in even if you have low freon or no freon. Once you know that compressor is ok then follow the direction as given by Arthur.

However, one big question is - Was ac working before and how long ago.? Are you sure there is no leak in the system. If there is leak in the system them ac will not hold the freon. To check the leak do it before you charge the ac with freon. Hook up vac line and see if vacum reading is persistanct for 24 hr. Arthur can put more chime on this.

Sahai