2002 Ford E-Series Van A/C Always Defrost


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MAKE: Ford
MODEL: E-450
: 2002
: 6.8 V10
DESCRIBE ISSUE.... A/C has three knobs. Fan Speed, Temperature, and Mode, including OFF. In any Mode but OFF, the A/C cools according to Fan Speed and Temperature knob settings, but air flow is always through Defrost Vents. I know Defrost is Default, the mode you get when there's no vacuum or the Mode valve fails.
I've found the vacuum supply line under the hood. There's vacuum to the connection where the tubing goes into the HVAC cabinet, engine compartment side. I need to get the "trim," "bezel" or whatever it's called, off to inspect the Mode valve/switch assembly. It runs from the left A/C vent, then Instrument Cluster, then a center vent, the HVAC controls (over the radio) then another center vent. The two center vents are above the engine doghouse. HOW does it come off? Two screws above the instrument cluster, remove headlight knob and nut, trim should pry/pull out. Right? But doesn't budge. What am I missing?

I have the Electrical and the Vacuum Diagrams. Vacuum shows a Reserve Tank, but where is it? With vacuum TO the HVAC cabinet, and no hissing inside the cabin, I think all I need is a Switch/Valve. I think the Valve will look like a Switch but with plastic vacuum tubing instead of wires...

THANKS!!! /s/jd
If you can't reach it through the top panel, give the front panel a manly tug and see if it will budge. Be sure to yell "Ford" just before you yank it. Or just pry behind it a little at a time with a trim tool.


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Will try that upper access panel, then some prying, pulling, yelling. Only "FORD" huh. Hopefully nothing worse.

Will pray I don't get involved in trying to access the Vacuum Canister!!!



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Looks like Pry I Must. Hopefully I won't need to dig all its guts out. The pic of the Vacuum Harness Connector shows what I expect to find on the back of the "switch" that I suspect is bad.


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I'm IN - Behind the Dash Bezel that the HVAC Panel of Three Switches lurks. I quit because of darkness, will have to remove the entire Bezel to gain any worthwhile access. Two screws up into the Dash above the Instrument Cluster, Headlight Knob and Screw-In Bezel (nut) they Pry and Pray. WOW it's tight.
Thought it'd come out as a flat panel but it turns out the Vent Deflectors, Radio, Lighter, and Power Outlet come off with it. Maybe Radio's attached to Bezel not Dash because it's aftermarket, mounted in a slip-in then bend-tabs "Mounting Can"
Hoped I'd see a connector off or disturb something that'd get it back to selecting modes but no joy. Started it up and air still comes only from Defrost Vents.
Case pends....


Wrench. I help when I can
Started it up and air still comes only from Defrost Vents.
Case pends....
Have you checked for stripped gears or jammed motors or vacuum leaks?? If all is ok, could you post BCM codes if there are any?
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Damn!! Sums up the current situation!! From the Engine, a Red Vacuum Hose connects to a Black Vacuum Hose (actually plastic tubing) Black disappears through Firewall near the Blower Cage. I got a diagram that says Black is Supply to the back of the Mode Select Switch (actually a Valve). Outputs from the Select Valve to the Servos are Red, White, Blue, Yellow.
I got the rest of the Bezel off and finally got the Vacuum Hose Connector off the back of the Select Valve. Two 10mm speed nuts... Started engine. NO, Zero, Zip, Nada Vacuum on Black or any of the other Hose Terminals.
So, Vacuum leaves the Engine and goes away somewhere between Engine and Select Valve. It seems there's Red-to-Black under the hood, then (where?) a Check Valve, then a Tee to a Vacuum Tank and on to the Select Valve.
Are some of the diagrams above telling us the Check Valve, Tee, and Tank are buried in the HVAC cabinet somewhere?
As stated above, Damn!!


Wrench. I help when I can
When the bezel is removed can you keep the select valve connected and listen for a vacuum hissing sound anywhere?? However, if you state there is no vacuum at selector valve, look elsewhere. Problem is probably on one of the vac supply lines.

Mobile Dan, bless him, provided a diagram of the vac tank. This reminds me of a cruise control that wont hold vacuum cuz the tank maybe pierced/ruptured or whatever english word I am trying to find. Lol!! This is in reply #3 of this thread. You must ascertain vacuum at that switch for proper operation of vents.

Trace the vacuum lines and look for cracks. There can't be that many. Over time, these become brittle and crack. Sometimes, someone goes in the engine bay and cracks one without knowing when changing plugs. or something close to the firewall. The leaks are small so drive-ability is not affected sometimes. Do you notice a idle issue? Up and down?
There's vacuum to the connection where the tubing goes into the HVAC cabinet, engine compartment side.
Confirm vacuum again there and trace back lines to mode vac switch. And don't forget to check the vac tank. If no vac, then is HAS TO BE SOMEWHERE IN BETWEEN.


Wrench. I help when I can
So, Vacuum leaves the Engine and goes away somewhere between Engine and Select Valve.
Again, trace those vac lines there. I am confident you will find it and have an epiphany or an aha moment!!;) You seem to have skills, and plz post a fixed or :beer:;):bat:when you get her done. All the best.




Wrench. I help when I can
The way I read the diagram I found, black is what you need to the check valve. There is only one vac line which provides to this unit, the back one. After that, it is the selector that does the rest.

If that is ok, move on to vac tank, if that is ok, then move on to connector 7 of diagram above. If vac is present there, but you state no vac, well we are at a stand still and you need to retrace your steps. If vac is present at check valve and not after it, replace the check valve. The check valve is there to hold vac in vac tank. Like I said before, it works like a cruise control. If you find a vac leak on that tank or black line, I have fixed them before with epoxy with good long term success, worth a try for a 2002. I like permatex epoxy. Maybe others can chime in also and tell us what they think.

Regards, hope this helps you. Nickb2


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Check and see if that vacuum line routes anywhere near the battery. A common GM issue with source HVAC vacuum lines was being damaged by acid where they were routed underneath the battery box.