Ideally yes you should vac the system, that will help it take a charge. It sounds like something else isn't right though. It would be nice if you had a set of high/low side gauges to get your pressures, otherwise it's just a guessing game. It's possible your compressor is toast if it's running and not cooling, but we don't have enough info to say for sure. If you replaced a hose and system was empty, the compressor should NOT be coming on unless it took some charge. Any idea on how much went in?
2004 Imola BMW ZHP
2006 Commander Limited Hemi QD2
"Bought, Not Built"