Originally Posted by BrianFred
I just picked up a 2001 Ranger 4.0 and am fixing up a few things that don't work properly. The cabin air is only blowing out through the defrost and I've now found that the vacuum canister line is broken. The line going through the firewall appears to be fine but the other line connected to the canister is severed. The only part of the line that I can find is attached to the canister and so I can't see where it leads to. I'm pretty sure it connects to the driver side of the intake manifold but haven't been able to find any clear diagrams to confirm exactly where. Can anyone tell me where this line should connect (or even better attach a picture)?
Try looking at the back of the intake manifold near the fire wall _ it will be out if site.
That's where the vacuum line port is located on my 3 liter, yours may be in a similar location.
There may be a large rubber boot with a number of different coloured vacuum lines coming out of it.
There should be one that's not connected to anything and it may be black or yellow.
Originally Posted by TheArcticWolf1911
The source of the vacuum is always the intake. I'm not sure how it creates vacuum, but it does. The heater control valve is operated by vacuum, doesn't produce vacuum.
The intake manifold itself doesn't create the vacuum.
The downward travel of the piston when the intake valve is open and the exhaust valve is closed creates what people perceive to be vacuum.
A vacuum tap from the intake manifold steels a bit of this vacuum (flow of atmosphere into an empty space of you like) and makes use of it to run the dash controls.
Vacuum is actually the flow of atmosphere into the engine as the piston travels in the downward motion. (the atmosphere has weight, about 14.7 lbs. per square inch at sea level, the higher you travel to the edge of the atmosphere the less atmosphere there is _ it will weigh less)
The atmosphere flows into the empty space as the piston travels downward, like pulling on a syringe.
The computer with its MAF sensor detects this flow and opens the injector at the right time to add fuel to the air traveling into the engine.
All this is timed just right using the crank shaft position and cam shaft sensors.