Center air outlets

On my 1985D/T there is no air from the center outlets. As I understand this from the owners manual there is a switch over that opens the flapper when
the system calls for air and closed it when the system calls for heat. My question where (physical) is that switch over located? It must be electrical that sends current to open the vacuum valve of the flapper.
Thanks Tom
1985 300 D/T 303000 one owner miles. 1978 450 SL Odometer shows 130000 miles title shows two previous owners 1966 Ranchero 102000 one owner miles
--
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com ).
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
my problem is the reverse
on my 84SD i looked behind the console scratched my head. pulled the tunnel off and opened the 2 flapper doors and got heat at the floor and turned the dash vents off by the slides.
the case, minus a few cans!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On the 123 body, it is very very rare to lose the center vent switchover valve. 9 times out of 10, the vacuum element is ripped. The other 1 out of 10 is the plastic pin broke that attaches the element arm to the center vent flap. The center vent element sits on top of the heater housing right under the middle of the dash. The hot sun cooks the area every day the car sits outside.....

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks Karl - will take a look see now that I know where to look. It was intermittent for a while whitch lead me to beleive it was the switchover valve.
Tom

this
when
My
--
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com ).
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tom, This situation is the default setting when there is not enough vacuum to operate the vacuum elements which control where the air comes out. You might have a leak. follow the vacuum line from the top of the vacuum pump on the front of the engine. Remove the left two lines and block the vacuum fitting with two golf tees. This experiment should do the trick and provide smoother shifting and smoother running engine. If it doesn't work, replace the vacuum hose coming off the vacuum pump with a piece of new vacuum hose and check all the plastic vacuum lines to make sure they are sealed at each end. You may need to replace the vacuum elements. Get a vacuum gauge for about $20 at Sears and remove the glove box lining. There is usually a vacuum bar with lines going to it. You can plug the vacuum gauge hose into each and see if it reads any vacuum. If some do, and some don't, you'll need to remove the dashboard to replace the vacuum elements. They are availble from Rusty (buymbparts.com) at 800-741-5252. P.

this
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.