HVAC Services: Climate Control & Repair

Hello.

Yesterday, I had the air conditioning system serviced on my Golf IV AJM, manufactured in 2001.

After evacuating the refrigerant, I wanted to drain the refrigerant oil from the service unit, but nothing came out.

A Sandem SD7V16 compressor is installed, and it has a screw located on the side, in the middle. Is it possible to drain the refrigerant oil from this screw? To do so, the compressor would need to be rotated 90 degrees so that the screw is at the lowest point.

Is it also normal that you can't extract any refrigerant oil with the service device?

I once heard that this is supposed to be the case with some newer air conditioning systems.

In a post by Michaell II (regarding draining the air conditioning system), it states that you should drain the oil from the compressor, but I'm not sure if the screw mentioned is the one used for draining.

PS: I performed the service in a warm garage, and I ran the air conditioning for a few minutes before evacuating the system.

Best regards.

Christian.