I finally got my heater core in, blower fan coming on, and heater case back together. Now the system is in defrost only. My question is where is the port for HVAC vacuum on the engine of an 87 LG4 auto car? I know I can use any manifold vacuum, but I'm trying to route everything correctly. Also where does the line come out of the firewall? I have a few broken lines so I'm wondering which is which, thanks.