ESP/ASR fault trying to vac test swirl valve for leaks

[jccamp]

I'm trying to follow this test procedure below and don't know which coupler to disconnect can anyone help? The left or right one?

To test the system a vac gauge needs to be connected into the system, I used some small plastic hose couplers purchased from B&Q and piece of suitable sized plastic pipe.
Removing the coupler on the TOP of the swirl valve EV connect a T piece into the silicon elbow a short length of pipe from the T piece to the top of the EV the other arm of the T piece is connected to the vac gauge.