Compressor will kick on with minimum pressure. If there is not enough quantity of refrigerant in the system, it can't generate a pressure differential to cause the temperature differential but also at least on some x5s, the system uses a variable orifice so there are some options of failure point.

I help maintain a bunch of cars and with only $70-80 for a manifold kit for measuring high and low pressure it paid for itself the first use. Learning the expected value and determining what the actual value is plus knowing what it is this year vs last year helps determine if it's wearing out.

I added an extra port so I can connect regular or quick connect R123a cans to mine. I also bought a $20 Venturi vacuum but ended up getting a real vacuum pump for about $80 which I traded for fixing a friend's AC. Paid for itself.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)