I had this vacuum hose sticking through the firewall, it wasn't connected to anything on the engine bay side of things, but it leads back to the little white connector for the aircon/header stuff. Has a tag on it still (luckily) and it's hose number 4, where the hell does it go? Cheers... Some original photos have not been recovered yet.

none of mine have numbers anymore lol, so i cant help there. if it is the one going through the firewall it should run down the RHS of the engine bay to a T near the battery and to the vacumm ball. if its disconnected your vent controls wont work. If its just one of the ones off the back of the valve on your A/C controlls then it will just be one specific vent that doesnt work. Only other vacuumm hose goes to the vac switch on your brake pedal for the cruise control. The only hose going through the firewall not connected to anything on the engine bay side is the drain from your A/C evaporator. Hope that helps out.

cheers, I will have a hunt around for a T joiner missing something Just laughing now, because I was defected for it! And told it was aftermarket haha! Some original photos have not been recovered yet.