hello i just installed my heater control head .it was out due to restoring car. its also been so long since ive driven th car i have no clue what its working conditoin was.the slider that indacates flap positions dosent jive with the actual flap position. the footwell flap is the only one that operates and remains open when it shouldnt. i reluctantly refered to my 1 of my 9 books to not be suprised at its uselessness. the diagram only gives me half of the info. it gives me vac diafram to hose color in german of corse it gives me hose color to some letters that only exist in the book. i then did the reliable method of trouble shooting , ignoring what the book says and try to figure out how it soposed to work. i removed head and applied vac pump to supply hoses and moved selection lever to find wich ports th vac travles through. in the footwell position there is passage but in the defrost or dash flaps ther is no vac passage whats going on ? can the head be faulty ? i opened the valve system to find it is very unlikley they are faulty. is anyone familiar with this system or have a diagram or pictures that make sense ? the car is a 78 i should of stated that erlier thanks much

 

I think that the vacuum diagram on Page 87-2 in Volume IV probably covers your system. It will take some study to understand the diagrams...

The black supply lines go to Port 1 on both L1 and L1 sections of the vacuum controls on the head. The diagrams then show which ports are connected in which lever position. Note that the heavy lines show vacuum flow, while the dashed lines show venting - that is, the ports are connected, but there is no vacuum flow. The vented ports allow the vacuum actuator to release.

I would suggest that you test each of the vacuum acturators to ensure that they hold vacuum - split diaphragms are the most common problem on the system.

 

This brings up a question I've had. Where are the vent ports routed? Per the diagram (and control head installation), white vacuum lines are attached to the vent ports and run behind the dash. When testing my system, I found that these lines do not hold vacuum -- I assume that this is normal because they are vents.

 

wally, the ports on the back of the head are arranged it 3 clusters a b c each numbred 1 to 5 i can find no corosspondance to that in the book. scott the diaframs vent through the valves

 

early 78s have a diff vac setup than the wsm indicates, if this is the problem you have I can upload the early diagram when I get home

 

that would be great thanks rixter

 

here's the vac diagram
credit goes to the 'lister who gave it to me 2 years ago

 

thanks for the diagram. i routed the hoses in accordance with with the diagram. the defrost flap dosent comply with the slider settings ,upper vent setting and defrost setting witch are the same flap. any ideas on this? thanks again

 

Have you been able to find where the white hose go?
I am in the same situation of finding that , if you know please let me know
Thank's

 

the white hose goes to the heater valve underneath the airbox. If you haven't replaced the heater valve it is a good idea, since they are know to fail eventually

 

Brian, on early cars the heater valve hose is orange. Not sure where the white hose belongs, the only one I recall seeing is in the engine bay. But then I wasn't paying much attention to vac lines last time I had the side cover off the console.

 

You're right Dave , my hose going to the heat valve , that i changed , was red or orange, My problem is the white one , anymore idea ?

 

Dave
Thats odd....but the early cars did have a two stage center flap too? I think there is 6 solenoids on the early cars vs 5 on the later cars? On the later cars the orange is the center/comb flap... I still don't know what the later cars center flap really does....I can't imagine what two worthless flaps will do? Unless the early cars don't have the setting motor?

 

Brian if you're talking about the vac solenoids, my car doesn't *have* any AFAIK... I sure can't find them on the wiring diagram either. Maybe that's why everything still works.

 

Dave
There isn't any behing the stereo in the center console....they have to be somewhere to control the flaps? Mine sure was a PITA to get out and fix!