I have ran lots of searches. Found specific info, that my 84 f150 with factory air has one year only obsolete cables. That’s right, cables, plural. The one I have intact opens to door to allow heat in, firewall door. The obsolete cable I’m missing hooks to bottom tab for factory hvac control From off through ac, heat, to finally defrost. This metal Belsen cable, or hvac control metal cable is missing entirely, so all I have is waist high heat, zero defrost.

here is where I’m lost, the hvac box has a vacuum solenoid to move internal flap to switch between hvac directed toward feet to up through waist or chest vents, finally to defrost vents. Does a metal Belsen cable, the one I do not have, run from my empty controller to the OUTSIDE of the metal controller leg for internal directional flap? I’ve never seen a hvac with both vacuum and mechanical on same flap control leg. I can see nowhere to fasten Belsen cable outer sheath for that flap either.

so, I badly need defrost, so I can unhook vacuum solenoid from directional internal door frame, and internal flap will fall to bottom of hvac, directing any and all future air flow to windshield. That’s only way I can see missing Belsen cable to hook up, on he same metal leg with vacuum can hooked to one side, and mechanical Belsen pull and push cable to other, or is it a rod I’m missing from hvac control second hvac flap, not the firewall one, the selection from floor up to defrost.

hard for me to know, can’t find pictures of 84 that shows where middle flap cable terminates or fastens and to what.

 

And I realize it’s supposed to default to defrost only, but mine stuck on chest vents. I don’t have ac compressor, and can live with defrost only. I do realize I’ll also have to cap little vacuum line that operates vacuum flap control solenoid to prevent vacuum leak.

 

I did not know the 84 as "1 year only" control using 2 cables?
Then you say the door uses vacuum but stuck on vents (chest high) and not defrost.

This setup sounds more like dealer AC added and not factory AC or maybe this high flow vent system or something like that I hear of posted as it has the chest high vents but no AC IIRC.
Can you take a picture or the control face and the back if you can but may not be able to with it in the truck and of the HVAC box under the hood so we can see what you have.
Dave ----

 

Will try Dave. I did not either, and unsure I’m right. Was going on searches and interpreted it that way, but now that I’m taking it apart more, and there are vacuum plug things on back of hvac control panel I can feel, I think that must be it. I can feel some soft vinyl tubing on back of where lower slide control switch.

 

WEll, at least I don’t think I’m missing a rare cable now. I think I’m missing a flap door inside my hvac box. THE solenoids are moving with vacuum and responding. I believe the flap came off metal directional rod. The metal rod is moving on top vacuum solenoid, but air flow doesn’t change to defrost vents. Could be mice ate through it, r dry rot or something. But I thnk I have to pull whole box to changeout goobered up directional flap.

 

You can see the hose nipples on the left side of the controls.
There is a manifold plug that has all hoses in it you pull off as a unit. This manifold is held to the vacuum switch with 2 nuts on plastic studs.
When you try and undo the nuts the studs break off. Here you can see what is left of the studs on either side of the nipples.


I cant remember if the hoses to the manifold are color coded or not but if there is enough to put hose on I can find where they go to.
Now the HVAC gets its vacuum from the motor thru a tree on the firewall then to a "juice can" on the fender with a check valve / Tee.
The tee / check valve keeps vacuum on the can / HVAC side and the vacuum going back to the motor when under power.
This supply goes into the HVAC box near the hood hinge along with another hose that goes to the vacuum motor on the top of the HVAC box by the hinge.
Both the supply & that other hose has a plug / coupler maybe a foot inside the cab that plugs into another 2 hoses leading to the control.
If everything inside is there half the battle is done but like I said I can get where each hose comes / goes just may take some time find where it is on line.

BTW if you have the radio out you might be able to use a mirror & light to so the back of the HVAC control & hoses and some of the vacuum motors. May also need to remove the pad from the top of the dash to see / get to the vacuum motors.
When I got my truck someone cut the dash to get the HVAC controls & radio out so I was missing everything.
Before I put the dash all together.


All together


What it started as but I used a AC truck dash to replace this mess!




Dave ----

 

My vacuum and vacuum stepper motors or solenoids, are all fine. It’s the final stepper solenoid that has the flap to make defrost, and it’s moving the metal rod via vacuum via control switch. You can see the bent flapper rod tip moving and opening and closing just fine, via controls. Yet, with no air flow change, from all way through range, everything just comes out waist level dash vents. No flow at all on defrost, despite vacuum motor pulling flapper rod arm. So, the flap must no longer exist inside the unit.
I even removed both vacuum pipes from the top vacuum solenoid, which should have caused default to defrost, and zero air is there at defrost. So, the internal flap is missing I think.


Works fine, heat

Vacuum in

First vacuum solenoid responds to vacuum and lower slide control

TOp vacuum solenoid, also responds to vacuum and slider control bottom of hvac panel. Moves metal arm which should be attached to flap

TOP slider control switch adjusts firewall door

 

Wait, if you were looking on here for information on the control cables I think there are different cables for different years and IIRC has to do with how they hook to the control (maybe box end?) of both inner & outer cables.
IIRC you can swap the control & cables as a whole unit and why I think the box ends may be the same.
It was a while ago I went thru all this for my truck and some of it is coming back now.
Dave ----

 

Pictures removed to save room and not needed at this time:
Ok it sounds like all the vacuum motors (silver cans with vacuum hoses to them) are working if I under stand you right and if so this is going some where I don't like to go
It almost sounds like what they call the blend door hinge has broken.
If you go up top to the FAQ or Tech Tips and do a look for blend door hinge it should give you a way to check if that is what the issue is and how to fix it.

When I first got mine together all worked as it should. Just before I got it on the road it only had defrost. After about an hour of checking everything I found no vacuum inside the cab to the control but had it in the engine bay? I found where the hoses came thru the HVAC box had cracked right at the rubber pass thru, once fix all was good.
In your case all sounds like the motors are working but still no change in air flow and why the blend door hinge issue.
Dave ----

 

I do have a question about 1 of the pictures.


What is the white block on the lower right side with the black wire to it?
Is that a light that comes on when the doors are open and if so is there a different color on that wire and where does it go to?
I ask because I would like to install under dash lights, cab light does not work and too hard to try and fix, and need to know how it is connected to the trucks system.
Thanks
Dave ----

 

Yes Dave, that is pass foot well courtesy light. Yep, I’d feel figured my solenoids and vacuum are ok, and I have a flapper door issue. So I think I’ll wind Up having to take it all out. Need to check what you attached before to further. Ice tea break now.

 

Are you talking about this?:

https://www.ford-trucks.com/forums/1...oor-hinge.html


The third paragraph describes how to check the operation of the actuator and door. You can see the vent door actuator just inboard of the glove box, without any disassembly. This horizontal actuator controls the door with the plastic flex hinge, the kind that easily breaks. When this hinge breaks, the door falls inward and air always comes out the vents on the face of the dash.

The other actuator is for the floor/defrost door, and is hidden behind the radio area. This actuator is vertical, and the door hinge is a metal rod that is pretty much indestructible. This door has three positions. When all the way down, there is no airflow through the floor vents. When the door is all the way up, there is no airflow to the defroster vents. When in the middle, airflow is split between the floor and defrost. But if the vent door hinge (mentioned above) has broken, most air escapes there instead of going to the floor and/or defrost.

 

Yep, that’s exactly what it was. I cut a shim the same size he suggested, jammed it where he suggested, and now have full time defrost, as he said. So, I’m good with that, and firewall door cable for heat control.
i might install an in-line heater hose valve in come spring, like my 68 f100 used to have. Then I could ensure heater core wasn’t warming up in warmer months. Which is most time around here.
As for now, I can use truck, because now I can clear the windshield, but still have center of dash plastic trim, radio, and pad and glovebox out in case I get more ambitious sooner.
So, been good holiday, with warm enough weather to “dirt mechanic”, and I’ve got my choke and cold stumble issues and lack of defroster resolved (for now). Thanks again, Odis.

 

I figured it was the door after your last post.
Being you have it mostly apart and it being cooler now it might be best to look into fixing it now as it is only going to get hotter outside.

When I had my truck out last it was kind of cool and raining and with out working AC I had to have the heat on defrost and the vent windows open to pull the hot air out to clean the glass.
I was also thinking it would be nice to have the vent shields over the door glass so I could crack then also. Then again it gets me to get the AC working sooner too.

Thanks on the light I will have to give a better look under the dash on both sides for where that light plugs in.
Dave ----

 

See #3 here, it's an add-on (optional) harness:
https://www.ford-trucks.com/forums/1...y-options.html