The yellow vacuum line splits into many yellow lines just above the unit and I assume these are the locks. Where does the uncolored line go to?

The unit stops buzzing shortly after A/C is switched on.

Also yesterday I stripped the rear deck, removing the rear headrest locking devices and the vacuum unit attached. Should the main line that attached to the headrest vacuum unit now be plugged??

The unit in the boot has been buzzing for a long time before I removed the rear deck equipment.

Also my car has a rough idle, which smooths out when A/C is in operation.
Jumping about 600-800 Revs at idle. Could this be related?

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Living sideways