El Camino Central Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter #1
What makes the center flap door vent to open? I can manually reach in there and pull it up which then air comes thru to the center vents. Once I open that vent door, I see a triangular door vent further down. I am able to push it down and up? What I need to know how do these vent doors operate or what makes them open or close? What actuator do I need to check? i am not getting any air thru the center vents. See foto's. BTW, I also found a metal hook inside when I opened the center door vent. Any ideas? See foto
 

Attachments

·
Registered
Joined
·
12,262 Posts
what year ?? what color?? what size trailer ball ??
[like the guys at the artozone]

I assume were looking at a Gbody
the center Duct Door is controlled with the double acting vacuum motor or actuator,,
it will have 2 vacuum hoses.. its ether defrost or vent or both... IIRC

its kinda in the center-ish under the dash on the duct box..
no vacuum and it will stay on defrost or heat [bottom]..

there all vacuum operated except the blend door, the hot or cold, it has a cable..
so check for vacuum supply first
 

·
Registered
Joined
·
2,556 Posts
I noticed in one of your other posts you commented...

"A/C was bypassed so controls are also inop. Previous owner put an on/off switch inside but even that is sketchy"

you may be running in circles if you've got an incomplete system to start with..
 

·
Registered
Joined
·
20 Posts
Discussion Starter #4
JJLT1,,,sorry, left out yr info. 1978, auto, 305. So I think I see the right actuator that controls that door. It has a yellow and blue vacuum lines going to it. I did find the blue line disconnected and was hoping after connected, that there would be air coming out center vent but no. OK but how does air get out the center vent when this door is always closed? If I open it manaully, UP, air does blow out center vent. So which vent is the blend door? Hey thanks for your input
 

·
Registered
Joined
·
20 Posts
Discussion Starter #5
O.D. Showtime..you are correct. I do need to update that post though. I was able to undo the mess the previous owner had done. Now the A/C turns on with control switch. So the only issue i have is no air coming out center vents. I was thinking it might be the A/C control switch($34) but still pondering that. Thank you O.D.
 

·
Registered
Joined
·
12,262 Posts
if you don't have any vacuum
start at the Vacuum Ball and trace it both ways..
to the motor and inside to the control panel..

those vacuum lines get brittle and break real easy,
replace them with vacuum tube or oil pressure gauge nylon hose..

check the vacuum ball too it has a check valve,
if it's hooked up wrong nothing will work ether..
 

·
Registered
Joined
·
2,556 Posts
Vacuum ball should be mounted under the hood on the HVAC case. There should be two lines that run from the interior through the firewall and into the engine compartment. Purple should run to vacuum ball and either white or grey to heater control valve installed in the heater hose. Vacuum ball gets vacuum from engine. Make sure those are intact as well.

oop JJLT1 beat me to some of this info
 

·
Registered
Joined
·
2,556 Posts
Here's a couple of pics...the line he's holding goes to the heater control valve in the heater hose...

128487


The one line held here is to engine vacuum for supply..

128488
 

·
Registered
Joined
·
20 Posts
Discussion Starter #10
yes, purple to ball, grey to heater control valve, check. the black hose goes to engine block for vacuum source. I pull hose and I feel vacuum. But how do I chk to see if vacuum is actually going out the purple hose? I pull it and nothing happens? facing the vacuu ball, vacuum source line is on left side, purple right side.Thanks
 

·
Registered
Joined
·
20 Posts
Discussion Starter #11
yes,,that is exactly my setup,,as you face your vacuum ball, vacuum source line on right and purple on left. gray to heater control valve. Now how do you check to see if there is any vacuum in the ball? I see you seem to have taken of heater hoses by the open metal hose I see there.
 

·
Registered
Joined
·
12,262 Posts
you can bypass the vacuum ball for testing,
its just for holding the doors where there at when you go wide-open on the throttle,
the manifold vacuum will drop off to nothing till you let off the throttle..

the check valve may be stuck,, or it may be cracked..
 
1 - 12 of 12 Posts
Top