I really hope somebody can help. 03 Expedition (another post just below this one on a related but separate issue). While replacing the expansion valve ***'y a vac line go broken. fixed that with tubing. Now I only get air flow through defroster. I have checked all lines under the hood for vac with a hand pump and they all hold air.

I understand the supply vac to the manual control know is not getting vac so it is defaulting to defrost only.

My problem is I cannot find the vac supply line going into the cab. the ONLY vac line I see going through the wall is the white line that comes out to control the MAX air hot water cut off valve on the heater water supply.

Where is the vac supply line going into the cab, exactly? A picture of the line entering the firewall would be greatly appreciated.

PS - I have the factory diagrams. nice, but useless since it doesn't show me how the vac goes from the reservoir to the switch inside the cab.

thanks so much

 

it only took me 8 hours of online reading and reading the ford oem manual (disk version) to figure this out.

all references talked about the vac supply line leading from a 3-way check valve (a disk about the size of a dime) on the vacuum line leading from the throttle body (vac source) to the left, between the end of the battery and the firewall. the only problem is that there was no supply line from the valve into the firewall. or so I thought.

the line does go in from a valve that is daisy chained off a 3 way check valve through a rubber grommet the also allows passage for the outcoming grey/white vac line that runs the hot water heater shut off valve when the AC is in MAX setting.

the black line going into the grommet got pulled out while doing other work on the AC. Here's where it when wierd. there is a vac line that comes up from what appears to be a juncture of vac lines that are involved with running the ABS and/or 4WD. the line that comes up is just open to the atmosphere. there is another line on the driver side that comes up and terminates right under the master cylinder between the air intake and the cruise control unit. there are TWO open vac lines. maybe they are vents. I duuno.

on the passenger side, when the AC control vac supply got pulled out of the grommet, it naturally came to rest right next to the vac 'vent' line. Not having studied the vac lines before, it was natural to assume that they should be connected together. WRONG!!!

I unplugged the vac line coming from the little check valve, and looked into the firewall grommet (head upside down in the engine bay to see there are two ports. So I litterally just stuck the vac line from the check valve into the 2nd port in the grommet and Voila~ now I have full control of the panel vents etc.

There was no diagram in the ford oem manual that would have showed the location of the supply line. I guess they figure in normal condition you would see that it came out. I just happen to read a post somewhere that had a guy with the vent line and he took a pic of it. then another post about the 2nd port in the grommet, then some more reading about how to check the system for vac leaks per the OEM manual.

what a lousy way to spend a sunday afternoon. At least it works now.

hope this helps somebody.