I have GEO (Suzuki) Tracker, 1994. Cpuldn't get a compressor so bought one for a 1997 model and had the attaching hose fittings changed. Everything else (bracket, belt etc.) was fine. I don't have a vacuum unit so I just put it back together and charged it. I've done that on several Fords in my life time and got cold ac. The GEO cools OK but low side is 46psi and still foamy in the sight glass. Before I got my guages I charged by simply watching the sight glass. Works OK also (not as good as now with less low side pressure and foamy sight guage. What should I check or do next?