'Sorry, but you don't need a vacuum pump. If you have good gauges, hooked up to the right ports, know the ambient air temp., and how much charge the system is supposed to have, you can fill the system properly without a problem. Eric '
REPLY: If the system is totally empty, you WILL need a vaccuum pump to rid the system of air and moisture and do it correctly. Further, you dont 'fill' an auto a/c system (to the top) ; it has to be accurately metered in and depends on a variety of factors . You will NOT know how much freon to put in unless you weigh in the EXACT amount which requires a Charging Cylinder that is marked off in lbs and ounce increments .. which requires you to know how to use it properly ; if y ou just add freon from a store bought kit , you are only guessing . If youre a consumer, stay away from touching your a/c system except to power wash your Condensor Coil routinely.