Reoccuring Surging of Aircon Chiller

Greeting!

May I request your usual assistance on this re-occuring surging concern on our aircon chiller. It has condensible gas present in the system so we normally do manual purging.

We have performed leak test and some leak points were observed. After we sealed of te areas and reprocess and recharge the system, surging was still experienced. What other causes resulted to this concern.

Thanks and hope to get your immediate response. Good day!