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AC Vacuum Modulator question


64riviera
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Today I decided to replace the vacuum lines because some one it was quite a mess of vacuum hose, with the strangest connections, that didn't look anything like the layout in my manual. Wondered how it could actually have worded, at least, it looked to me like it all worked.

 

But like I said, I started replacing al the vacuum hoses and make the connections like the way it was mentioned in the manual. But then I saw a strange thing attached to the controle unit. After some research I found out that it was the AC vacuum modulator. This modulator has two connections, a larger and a smaller one.

I found out that the smaller one goes to the vacuum diaphragm under the hood, but where to large connection has to be connected to?? No idea. Can't find it in the manual.

In the old situation it was connected to the main vacuum source (the smaller tube that comes from the vacuum storage canister), but since the connection is larger I expect it to be connection to something else.

 

Then I also remembered reading something about the drawing of the vacuum circuit  in the manual being wrong. The two dual stage vacuum diaphragms where switched in the drawing in the manual. Anybody know if this is thru?

 

I attached some pictures of the AC vacuum modulator I'm talking of.

 

 

20181128_193328.jpg

20181128_193334.jpg

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On the 1963 Buick Service Manual figure 11-78 shows where the vacuum modulator hoses connect in the engine bay. On mine, one of the hoses goes to the STV and the other connects T’s into a vacuum hose. The vacuum hoses are color coded by the factory and OlD Air sells the set of vacuum hoses that correspond with the factory color hose marking. 

Id venture to speculate the 64 Buick Service Manual can show you where the hoses connect.

 

RRB

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Hi Bob.

Yes there's a figure in the 64 manual showing where the vacuum hoses go, but the vacuum modulator is not shown in that figure.

I know the she smaller connection  goes to the STV and the bigger one T's into another vacuum hose, but it doesn't show into which vacuum hose. And there a quite a couple of those vacuum hoses.. 

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Thanks Bob for the schematics. The '63 is different from the '64, but it looks like the bigger connections from the modulator T's in to the vacuum hose that goes too the "outer" connection from that dual stage diaphragm.

If I would compare that to the schematics from my '64 this would be the vacuum line coming from the nr. 4 connection from the heater adapter (marked yellow).

20181130_195319.jpg

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On 12/5/2018 at 12:37 PM, 64riviera said:

Thanks Bob for the schematics. The '63 is different from the '64, but it looks like the bigger connections from the modulator T's in to the vacuum hose that goes too the "outer" connection from that dual stage diaphragm.

If I would compare that to the schematics from my '64 this would be the vacuum line coming from the nr. 4 connection from the heater adapter (marked yellow).

20181130_195319.jpg

Sir, you are correct.

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On 12/5/2018 at 8:18 AM, telriv said:

Lets not forget 1964 is set-up slightly diff. than 1963.  '64 Riv. I hope your looking at a 64 chassis manual.

Tom, I did alert the gent I WAS looking at the 63 Service Manual. I also alerted the gent of/there may be a difference. Seems as though the gent is on top of his game and all is understood.

RRB

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The 64 isn't slightly different it's totally different.  On the '63, vacuum comes from a T with a valve in it.  That T goes into a port on the front of the intake manifold.  One half the T goes to the a/c controls on the passenger inner fender, the other half of the T goes to the power brake booster.  Switches for the a/c are on the inner fender for the 63 and are controlled by  set of bowden cables and leverls.  The 64 switches are in the console.  About as much alike as Laurel and Hardy..  They do share the use of two identical dual stage diaphragms though

 

If your 63 is complete, the schematic for the vacuum lines is embossed on the cover for the a/c controls

 

Here's an excerpt from a whole bunch of tech tips that have a link on the ROA's website.  Can anyone verify the note at the bottom about the 64 shop manual showing two lines being reversed?

http://www.chip.com/buick/techtips/dual-stage.html

 

Heres a link to the menu of tech tips from Chip Little from which i chose the one above.

 

http://www.chip.com/buick/

 

 

 

 

 

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6 hours ago, RivNut said:

The 64 isn't slightly different it's totally different.  On the '63, vacuum comes from a T with a valve in it.  That T goes into a port on the front of the intake manifold.  One half the T goes to the a/c controls on the passenger inner fender, the other half of the T goes to the power brake booster.  Switches for the a/c are on the inner fender for the 63 and are controlled by  set of bowden cables and leverls.  The 64 switches are in the console.  About as much alike as Laurel and Hardy..  They do share the use of two identical dual stage diaphragms though

 

If your 63 is complete, the schematic for the vacuum lines is embossed on the cover for the a/c controls

 

Here's an excerpt from a whole bunch of tech tips that have a link on the ROA's website.  Can anyone verify the note at the bottom about the 64 shop manual showing two lines being reversed?

http://www.chip.com/buick/techtips/dual-stage.html

 

Heres a link to the menu of tech tips from Chip Little from which i chose the one above.

 

http://www.chip.com/buick/

 

 

 

 

 

It is true the schematic is embossed on the front of my vacuum switch cover, but it is not very good in helping to figure out what goes where. The color coded black vacuum hose from the check valve does go to the a/c controls on the inner fender. The black vacuum hose from the check valve makes a number of intersections before ending up in the middle port of the #1 vacuum actuator. In the case you substitute the 63 water control valve with a vacuum water control ( 1964 ) the vacuum water control taps into the black color coded vacuum line before the black line terminates in the middle port of the #1 vacuum actuator. The AC on the 63 can work with a single dual port vacuum actuator as #3 while the #4 vacuum actuator is eliminated.

There are two line coming from the vacuum modulator in the 63. The large line from the vacuum mod goes to the port on vacuum actuator on top of the STV. The small line from the vacuum modulator taps into the line that goes to the top port of the #1 vacuum actuator.

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