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Thanks for the photos GTO Jr. Because I am also cleaning up the rat nest of wiring under the dash I have the radio, ductwork and glove box removed already. I can see inside the plenum and see the actuator but cannot get my hands in there. Just what does this actuator actuate?

I removed all the nuts holding on the plenum including those on the bottom that required Cirque de Solel grade contorting, removing some inner fender bolts, swivel sockets and ratchet wrenches. This thing was glued in place with some black silicone stuff and while I can pull it off the firewall it seems to be held back by something. Perhaps the ductwork that goes into the fender. When I can get back out there I may try removing more inner fender bolts to see what is holding it back. When I reassemble should I use some dumdum type sealant? I used black silicone on my Camaro but looking back maybe I should not have.

This is a nice car belonging to a colleague at work. I agreed to work on it and he agreed to pay me for my efforts. It is a older restoration with dried seals, belts and holes, heat didn't work, AC doesn't work and various other ailments. I'm having fun and making a few bucks but this thing is whooping me.

My old car is a '69 Camaro I built twelve years ago. Some photos on the sister site. Team Camaro Showroom - Andrew69 Gallery

Thanks again for your help.

Andrew
 

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Yes the plenum is sealed very well from the factory and will require a lot of effort to release.
You shouldn't have to touch the fender if you remove the duct between the Evaporator & Plenum cases.
This is also sealed at each end so go slow as I'm not sure this is avail.
Once off it will reveal a bolt if you already haven't seen it.

IIRC the actuator your after controls the inlet vent.
The single port actuator in that location now is similar if not exactly like the one mounted on the interior side used to control the defrost door.

Once your at the point of re-installation 3M Strip caulk is a great choice for sealing things such as this.
 

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That duct you mention I have the screws removed from the top but didn't see those on the bottom. I'll remove them too and then this thing should pull straight off. I did remove that hidden nut you identified. Today I see this duct has screws inside the fender area that I cannot easily reach. Wish the fender well was removable without messing with the fender.

This has been off before based on the excessive sealant across the top edge and mismatched small screws on the upper half of the duct. The upper screws on the plenum don't seem to be gripping any metal. Either they were stripped out or the screws used are too small. From memory they are 5/16" sheet metal screws. What is correct? If 5/16" I may back the metal with something to grip or might use 3/8" screws.

With the help of both of you my confidence is restored. I hope once I get the under dash wiring straightened up and this plenum corrected he will have both heat and AC. I found he had no heat because a connector on the sliding switches was incorrectly connected and it blew the heat fuse every time you turned it on. I figured while I have the fan motor out I might change it out too.

Oh, and even though things are tight I am glad I don't have to remove the fender.

Thank you.
 

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Sorry for the noob question, but why in the world would vacuum lines be used with the HVAC system ? I am sure my 65' convertible doesn't have this....What am I missing ??? Thanks
 

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The vacuum is used to open and close doors in the air ducts to direct to floor, forward or defrost. Your car might use cables to do the same, but I don't know the '65 models.
 

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Something seems to be amiss, The Pink/Brown lamp is ammeter, which indicates you have standard gauges Vs rally.
The odd thing is the Dark blue lead connector end isn't correct for lights(standard Gauges) ?? but should be oil PSI related.
 

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This is the dash in this car. I have no idea what a previous owner might have done. I imagine this the standard gauge package considering the lack of tachometer.

Update: Yesterday I pulled the dash carrier back looking for the elusive socket to plug that lamp. It turns on with the oil pressure idiot light when I turn the key to the first stop position so it is warning light related. For now I will remove the bulb and tie it out of the way in an accessible location.
The blue wire seems like it should plug into a spade on the back of a gauge. Like the lamp I cannot fine a logical place to plug it. So for now will leave it unplugged.
What I don't know is if someone in the past made changes to the dash gauges without updating the wiring.
If anyone has any better ideas please jump in.
 

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Update: I absolutely could not get the heater box out so the fender came off. Now that I could see behind it I found the clamp screw for the upper heater hose was blocking the unit from pulling away. :-(

I now have it apart and will order the new actuator but first this needs cleaning and painting. Anyone know where I can get the plug thingy for the 3 hoses and wiring pass through?

What is the correct color of black for the heater box? Gloss black or semi flat?
 

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The blue wire pictured above does not go to above the oil filter but instead disappears behind the firewall padding routed towards the floor. I applied power to see if anything happens with no obvious results. Removed the door sill and pulled up the carpet and didn't spot it. Still puzzled. Maybe it is a rogue wire someone added that is no longer utilized.

:confused:
 

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Today I am to the point of figuring out which vacuum hose goes where. The upper slide has these markings:

DE-ICE HEAT OFF VENT OUT INSIDE

DE-ICE - LH actuator pulls defrost door to direct air to the windshield
HEAT - LH Actuator releases to allow air to floor
Off - No vacuum to anywhere (Correct?)
VENT - Air inlet pulled open and Diverter Door open to circulate into cabin
OUT - AC on with fresh air (Air inlet open)
INSIDE - AC on with recirculate (Air inlet closed)

I routed the lines based on the attached diagram. I find the firewall mounted actuator does not release whenhe slide is set to INSIDE. I can also hear a leak when slide is set to OUT. Because I am testing with a hand pumped vacuum it is difficult to find the leak.

I need to know which of these go where and the possibility of the slide valves needing repair or replacement. Is this manifold numbered counterclockwise beginning at the 5:00 position?

Am I making any sense?
 

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For the benefit of someone else with the same question:

Using my Mityvac to pull a vacuum I tested all options of vacuum draw and which ports are open when the climate selectors are made. It seems the chart is correct as long as you follow the numbering on the manifold, which is numbered clockwise. You cannot see it unless you remove it from the dash.

Port Application
1 Actuator on firewall primary line
2 Actuator on firewall secondary line
3 Manifold vacuum
4 Actuator to direct air to defrost
5 Actuator to direct air through AC ducts
 

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help i need a diagram of the vacuum lines for the air con , i didnot take the car appart so i dont know where any of the hoses go any help would be great thanks:confused
Hello please, Can someone help me, I am connecting the air conditioning of a 1966 Pontiac GTO and I do not know where it is connected what is underlined in the image,
WhatsApp Image 2021-04-07 at 1.35.54 PM.jpeg
 

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help i need a diagram of the vacuum lines for the air con , i didnot take the car appart so i dont know where any of the hoses go any help would be great thanks:confused
Hello please, Can someone help me, I am connecting the air conditioning of a 1966 Pontiac GTO and I do not know where it is connected what is underlined in the image,
WhatsApp Image 2021-04-07 at 1.35.54 PM.jpeg
WhatsApp Image 2021-04-07 at 1.35.54 PM.jpeg
 
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