What fitting do I need to apply vacuum to the system?

[R8rPhan]

Restoring the AC/Heat system on my squarebody...

Just noticed that the little hard vacuum line that comes through the firewall into the engine bay is no hooked up to anything...

Where is this line generally hooked up to?

Can I tee into the vacuum advance line for the distributor?

Anyone know what size that little vacuum line is or what kind of fitting I need to get vacuum on it?

I need to get it working so I can operate the controls and get the 7mm socket I just dropped into the defrost outlet, out of the ducts.. I rattled the ducting and heard it finish dropping all the way down.. I took the little outlet off the bottom of the housing, but there is a vacuum operated door just above it and I'm pretty sure the socket is right there...

Virtually 90% of the screws on my dash are 7mm, so I'm not going to get very far without that socket...

 

[R8rPhan]

NEVERMIND!

I found where it connects.. There's a vacuum reservoir next to the AC stuff with a fitting on the bottom...

All the controls work now..

 

[74 Shortbed]

That means you got your socket back too, progress is on the upscale now..

 

[R8rPhan]

Nope, can't get the socket back.. The door doesn't so what I thought (hoped) it did... Only way I'll be able to get it back is to remove the valve and door... Not even sure how that is done....

 

[chengny]

Nope, can't get the socket back.. The door doesn't so what I thought (hoped) it did... Only way I'll be able to get it back is to remove the valve and door... Not even sure how that is done....

It probably fell all the way down to the bottom of the defrost uptake plenum and has settled on the top surface of the defrost damper:

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That is a tough area to access. Here is how your air handling system lays out:

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Note that the defrost damper extends almost all the way across the length of the box. That effectively blocks any access to the top surface of the damper.

Also, even if you removed the distributor duct from the main plenum, that wouldn't allow access - because the diverter valve is hinged on the side that is adjacent to the defrost damper chamber:

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.

The main body of the plenum can't be dropped down without releasing it from the firewall and there is no room to remove the "whale tail" that supplies the defrost vents without dropping the main plenum.

If you really want that socket back I would consider drilling a neat access hole in the front of the defrost damper chamber and - after retrieving the socket - sealing it back up with a rubber body plug.

 

[R8rPhan]

Yeah, I was hoping that the valve opened in such a way that the thing would drop out through the heat outlet to the floor.. But it doesn't..

Short of maybe fishing a magnet on a string/wire down there, the socket is probably part of the truck now... Definitely not going to go through the hassle of tearing the ducting back down again to get it out.. It was hard enough putting it back together as it was...

But a magnet is more likely to just stick to the damper door and never catch the socket...

Sooo.. I guess I gotta buy a new mini metric socket set..

But I can definitely hear when the damper opens and closes now by the sound of the little socket rolling back and forth..

I'm thinking I want to put some sort of grating over those openings before anything important falls down there... Will do that when Ii replace the dash pad... Maybe make something nice out of ABS...

 

[R8rPhan]

I do have another question though...

The fan switch works in that I can select low, med, and high, and hear and feel the change in fan speed (although it seems like high should be higher than it is, but not sure), but when I set it all the way to low, and then switch the top slider to 'off' I can hear the fan still running.. Is this normal?

I would think that the fan should be 'off' at that point, but I don't know as I'm not sure how it's supposed to work..

 

[74 Shortbed]

That's the way they are, it came from the factory that way, the idea is to keep fressh air in the ducts to prevent mildew buidup.

 

[R8rPhan]

That's the way they are, it came from the factory that way, the idea is to keep fressh air in the ducts to prevent mildew buidup.

Okay cool! I figured it was probably supposed to be that way, as that would be a crazy way to 'fail'..

As far as blower speed, I guess I probably shouldn't worry about that either as the cab gets hot in a hurry when the heater is on...

 

[74 Shortbed]

Okay cool! I figured it was probably supposed to be that way, as that would be a crazy way to 'fail'..

As far as blower speed, I guess I probably shouldn't worry about that either as the cab gets hot in a hurry when the heater is on...

As long as the heater core is good, it'll cook ya quick..

 

[R8rPhan]

As long as the heater core is good, it'll cook ya quick..

The Radiator, hoses and heater core hoses all look brand new.. I suspect that the reason all those heater duct parts were missing is because someone replaced the core...

 

[74 Shortbed]

The Radiator, hoses and heater core hoses all look brand new.. I suspect that the reason all those heater duct parts were missing is because someone replaced the core...

Very possible, you'll find out soon enough.