Possibly related to these guys.
Where do all the vacuum lines go on a VG30E engine?
- Z31 Vacuum Lines Diagrams & Replacement at thumper300zx.com
- 1987 Nissan 300zx Non Turbo: Episode 27 Vlog: Vacuum Hose Routing video from LastHumansGarage
- Hot air from AC vents from xenonz31.com (archive) – also this
- Photos of vac lines with sizes from garymolitor.com
- Vacuum tank fix zdriver.com
Heating and Air Conditioning Refreshing at xenonzcar.com