That is the vacuum supply for the HVAC control.
02 sensor
Directly behind the intake manifold with 4 10mm bolts on each corner, there is a 1 inch thick black vacuum hose coming out of the the bottom and 2 clips with wires attached to it coming from it as well
On a 1998 Windstar the vacuum reservoir tank is under the hood in the back left of the engine compartment when standing in front of the vehicle. Mine has a red and black vacuum hose coming out of it.
Possibly for the optional Cruise control.
Could be the vacuum canister yes, could be
The vacuum hose is probably 5/32" ID. The other question I don't have the answer.
Black dog
A vacuum and a black hole are two very different things.
I found mine by locating where all the steam was coming out when the plastic Valve broke....I have a Dodge Ram Van, left side, behind battery is a black box, coming out of that box are two 5/8" dia hoses, top hose about 10-12" away is a control valve with a vacuum actuator attached to it. I am currently looking for a replacement, cant find one online
If the floor and defrost vents are both operating and you can't change air flow to any other vents, the dash control unit does not have a vacuum source. This vacuum comes into the cabin from under the hood. Look for a black plastic line coming through the firewall near the blower motor on the passenger side. This line should attach to a vacuum canister. The canister is generally round black plastic. What usually happens is the vacuum hose gets knocked off or the plastic line may break.
The company that manufactures the Dust Buster vacuum is Black & Decker. The Dust Buster vacuum by Black & Decker is typically a handheld cordless vacuum.
The best vacuum cleaner is the Black and Decker PD1200. However if you are looking for a handheld cleaner then the best is the Black and Decker PV1825N.