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panel air selector

Hi guys. When move the levers to the right to change the air output, nothing happens on the floor or dash setting. Defrost is ok. If I remember correctly my 1973 El Camino had vacuum lines running to the back of the selector and if one had a leak it would not work on that setting. Does the 1973 F100 have the same thing or is it a different setup? Do I need to remove the whole thing from the panel to inspect it? When I get the AC converted on this thing I will want to be able to use those settings. Thanks for any suggestions.

Donald.
 

DNFXDLI

The Token Canadian
Staff member

Fellro

Moderator
Staff member
Factory air or no?
 
Fellro, I might be wrong but I believe it is factory air. I have provided a photo. I will have the AC converted soon and hope it holds pressure and can be operated but as of now I have 260 AC! YelloThumbUp
But even so, the selector only works on defrost. But when I turn the fan up it puts out a lot of air!!

Donald
 

Attachments

  • ac 2.jpg

Fellro

Moderator
Staff member
Might be, but need to see the air box, as that tells the story better. All a/c systems have a pump, and many aftermarket units of that day did use the York compressors. However, I think I see a little of the air box and if so it would be factory, so then vacuum control. The dealer air systems or non-a/c systems I think had cables, not vacuum control was why I asked. When there is no vacuum, the system defaults to defrost.
 
air box?

Here are two photos. Is this the air box. Sorry if I sound ignorant but I am still learning my way around this truck.
 

Attachments

  • airbox 1.jpg
  • airbox 2.jpg
the ez thing to check is the vacuum line to the vacuum canister on the drivers side fender. Mine looks like a black softball but I think some might have looked like a coffee can. Not sure on your year of truck. Mine was disconnected and sitting on the fender. reconnected and all vents work as expected. You should have a vacuum supply line to that canister I think from the vacuum tree on the back of the motor. See if that helps, if not we can get more technical from there.

I find a mityvac to be invaluable on these older trucks. Using this tool you can check the following to trouble shoot your system
1. Plug the vacuum line from the motor to the mityvac, with the engine running you should have a solid vacuum reading.
2. Plug that line into the vacuum canister, then connect the mityvac to the outlet of the vacuum canister. You should see the exact same reading as test 1.

From here you don't need the engine running, you can use the mytivac to supply the vacuum.

3. If this is all good and the vents still do not work, I would do a leak check, plug the mityvac into the line going to the cab and hand pump it down. if you cannot hold a vacuum there you have a leak or something has become disconnected.
4. Next you will need to get to the back of the control unit. There is a soft vacuum manifold that connects to the back of the selector. It needs to be seated to work correctly.
5. If that still does not work, You should be able to use the mityvac here again to test each line and see what is leaking. Start with the inlet line, not sure which one it is but I think it is fairly obvious. From there I am not sure, didn't have to get this deep on mine. Hopefully someone else on here can lend a further hand.

Good luck.
 

BKW

Ford Parts Guru
Hi guys. When move the levers to the right to change the air output, nothing happens on the floor or dash setting. Defrost is ok. If I remember correctly my 1973 El Camino had vacuum lines running to the back of the selector and if one had a leak it would not work on that setting.

Does the 1973 F100 with factory installed integral A/C have the same thing or is it a different setup?
Similar.
Look at the parts catalog pic for 19B888 .. This is the A/C Vacuum Controlled Selector Valve Assy.

It mounts to the backside of the A/C-heater control panel, all the vacuum line connect to it.

When you slide the lever on the panel, this valve opens one door, closes another.

Besides this puppy, there are several blend door motors, shown as 18A318 in pic.

If the vacuum lines become cracked where they attach to these motors, the blend doors won't work.
 

Attachments

  • 20161008142516.jpg
Last edited:
Many thanks guys for the very helpful info. With your instructions and attachments I am sure I can trace this down. Shouldn't be a problem. :)

Highest regards, Donald
 

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