Videos are probably from completely empty systems. If it's empty, the pump mostly pulls atmosphere out of it. A good system vacuum will suck in a complete R134 can. The second can goes in when it's running. Using temp/pressure chart, it's easy to charge up properly. Plus don't go over too much over its capacity. The auto temps settings in mine really don't work. Otherwise, it wouldn't get to 42F driving around.

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'06 X5 3.0i - bought @143,123 miles (12/26/20)