AC/Heater/Defrost switch erratic

Newbie here, so bear with me please. The truck is a 2002 E350 Diesel. The problem is the switch that selects floor/mix/ac/acmax/defrost now only blows air out to the defrosters. The air
is cold in AC, but no longer comes out of the vents.
The switch shuts off as it should. Is this a bad switch, an air diverter? issue?
Any help would surely be appreciated as it is a work van and leaving it at Ford for 2 days would kill me.
If this is a vague diagnosis, I'm sorry. Ask me some questions if I missed anything and I'll be happy to answer them.
Thanks in advance.
Harry ____________________________________________________________________________ __________ The Internets Premier Safe and Security SuperStore. Safes, Key Machines, Keyblanks, Specialty Tools, Door Closers, Hinges, and EVERYTHING else Security. www.mysecuritypro.com
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Usually when it blows out the defrost only you have a vacuum leak to the controls. Most likely under the hood on the pass side.
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Am I looking for a broken or cracked hose? These are the hoses that are approximately 1/4" in diameter correct?
Thanks for your post. It has me starting somewhere.
Harry

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yes, they usually go in through the firewall onthe pass side. Sometimes they are smaller than a 1/4 inch and made of plastic. If that is the case and its broken, you can use a rubber hose of about a 1/4 inch as a connector of sorts to fix the broken place.
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Thanks for taking the time to reply to my post. It wound up being a cracked vacuum hose in the REAR of the vehicle. The E350 was set up for rear air as an option and the hose was run to the back but connected to nothing. I cut the hose before the crack and plugged it and everything is fine. That was a fun job.
Thanks again,
Harry

they
its
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how did you find it?

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I could not find a hose coming out of the firewall, so I dismantled the dash and found the plastic hose. I followed the hose until I found the crack which was in the rear of the van. After finding it lead to nothing, I cut the bad section out and plugged it. Voila. 2 1/2 hours later...done. Knowing what I know now, it could have been done in 15 minutes as no dash disassembly needed to be done.
Harry

Sometimes
and
of
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