Yes, the system has a built in protection for the compressor to not turn on the compressor if there is no refrigerant. The climate control shows operating pressure in bars. I find on my car it is in the 8-16 range when operating properly and the system running.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record