Plants of window type air conditioning systems shut?

I work in the Philippines, where most air conditioners window type has no port for adding refrigerant. It is supposed to be a pinch connector you can use to pierce the line for maintenance. The turgor remains in the line permanently. Where can I find more information about this adapter or pinching for maintenance or recovery of a sealed air-conditioning systems?

Bolt for the service ports are available in most houses HVAC supply in the United States. These work well for recovery, but tend to leak if left in a system if I do want to put in everything that goes back into service.

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