Where does this wire go?

[Vdevice]

Hi all, need some help finding where this wire attaches too. The first pic shows it coming out of the rear firewall. And the next two shows the wire.

 

[TobyU]

It's a vacuum hose and goes on the small port in the middle of the heater control valve in the heater hose right below the green ground bolt in the pic.

 

[Vdevice]

Thanks Toby