We have split a/c unit, the brand is Carrier-a water cooled condenser, water from the water chiller scroll type of compressor. Just 1 month ago, I experienced low suction. I made leak testing from the evaporator to condenser but no leak found. I tried to vacuum the unit inorder to check if it is leaking nothing goes wrong. Everytime I charged refrigerant the pressure goes to 2.5 bar then slowly goes to 2 bar, then tripped. When I fully charge, the compressor stops it takes me time to bleed. I already changed liquid filter nothng happened. I adjust the flow of water from the condensing pressure of 14 Bar to 11 Bar, it seems it take long to tripped but still the pressure is reducing. I suspect that the evaporator pressure regulator or the compressor something doing this problem.

Can anyone share your ideas.