Vacuum leaks

[45acpJr]

Hey guys can someone help explain to me what on these trucks operates with vacuum pressure? My truck is hard to start when cold and I have been told that a vacuum leak might be some of the cause. I would like to get rid of what is not needed. I know the air conditioning and heater is affected but I don't know how that operates, also there is the vent on the passenger side what does that do? For what it's worth I am ditching the factory heat and air components eventually and putting in a vintage air unit

 

[y5mgisi]

After the HVAC, its just the vac advance, power brakes, and depending on carb, the choke pull off(s). Maybe you have an emissions era truck? That would also have potentially a vacuum line going to the little heat riser valve and EGR valve.

What carb do you have? If its a qjet, probably the fuel bowl casting plugs are leaking.