Vaccum is at -10 when defroster/air goes on?

[GinNBoost]

i have a major vaccum leak but I dont know where exactly it would be coming from because i havent gotten around to making a boost leak tester. Right now whenever I idle with no other things on (AC, defroster, etc.) my vaccum reads around -16, -17....but when I turn any of those options on, it raises up to -10 at idle. Anyone know where that leak could be coming from? All these leaks began right after I installed my Greddy Type S too...any help would be great. Especially help on making a proper and accurate boost leak tester because I heard the VFAQ one is garbage. Thanks.

 

[Defiant]

When the AC comes on, an air passage opens up to bump the idle up. There's your loss with the AC/defroster.

Your other leak is going to be a treasure hunt.