1963 vacuum diaphragms

[ytr1903]

Still working on the HVAC on my 1963. First off, I drew a blue line in the picture that I have attached. It is pointing at a hole in the firewall that doesn't seem to have a purpose concerning the HVAC. Is this hole there as an access point for something under the dash? What is its purpose?

Onto the more important issues, though. The diaphragm under the duct by the blower motor does not hold vacuum in either nipple. Is there a replacement that will mount and operate as the original? If so, where do I purchase it? 

The diaphragm between the suction throttle valve and the blower box only holds vacuum in the upper nipple, the lower nipple does not hold vacuum. Same questions as above, is there a replacement that will mount and operate as the original? If so, where do I purchase it?

Surprisingly, the STV holds vacuum.

Thanks. Any help is appreciated.

Tom

[Chasander]

I believe your looking at air intake and recirculating for HVAC

[Chasander]

Looks like Evapotator missing

[Jim Cannon]

2 hours ago, ytr1903 said:

Still working on the HVAC on my 1963. First off, I drew a blue line in the picture that I have attached. It is pointing at a hole in the firewall that doesn't seem to have a purpose concerning the HVAC. Is this hole there as an access point for something under the dash? What is its purpose?

Onto the more important issues, though. The diaphragm under the duct by the blower motor does not hold vacuum in either nipple. Is there a replacement that will mount and operate as the original? If so, where do I purchase it? 

The diaphragm between the suction throttle valve and the blower box only holds vacuum in the upper nipple, the lower nipple does not hold vacuum. Same questions as above, is there a replacement that will mount and operate as the original? If so, where do I purchase it?

Surprisingly, the STV holds vacuum.

Thanks. Any help is appreciated.

Tom

The upper rectangular hole in the firewall is fresh air into the A/C system.  There is a flapper that controls the blend of recirculated air vs. fresh outside air. When no A/C is on at all, the flapper closes off outside air from coming in.

 

When testing the vacuum diaphragm over between the blower motor and the STV, you must apply vacuum to BOTH nipples to test the inside (center) nipple.  If the outer nipple is exposed to air, the inner one will act like it is leaking.  Put vacuum only on the outer nipple to get the flapper to move 1/2 way (some air out on floor vents, some air out of dash vents).  Apply vacuum to both to get the flapper to move to its full inward travel (all air to dash vents).

 

The double can unit under the blower motor is not available new, only used parts car stuff, but can be replaced with a new single can, like you have up on the firewall. There was a recent post about this on this board that refers back to an old post of mine. You use the single can unit, you use a T-fitting to apply vacuum to both nipples when you want full outside air, and you plug off the other vacuum line (for partial recirc) with a golf tee.

 

 

[ytr1903]

Thanks for the responses. 

 

Jim, I tested the can between the blower motor and the STV just as you suggested. The can works perfectly. 

 

I also went on the Old Air website and found two vacuum actuators that might fill the bill:

https://www.oldairproducts.com/product/23-5965-vacuum-actuator

https://www.oldairproducts.com/product/23-5960-vacuum-actuator

Is one of these the proper actuator for my application?

Tom

 

 

[Jim Cannon]

On 9/7/2022 at 7:52 PM, ytr1903 said:

Thanks for the responses. 

 

Jim, I tested the can between the blower motor and the STV just as you suggested. The can works perfectly. 

 

I also went on the Old Air website and found two vacuum actuators that might fill the bill:

https://www.oldairproducts.com/product/23-5965-vacuum-actuator

https://www.oldairproducts.com/product/23-5960-vacuum-actuator

Is one of these the proper actuator for my application?

Tom

 

 

No, those are not the correct actuators.  You want a single port. You will not use the other vacuum line to the second can, you will plug it.

 

I don't have a part number for them, maybe someone else will.

 

Glad your other diaphragm tested good.

 

Edited September 9, 2022 by Jim Cannon (see edit history)

[Riviera63]

11 hours ago, ytr1903 said:

Thanks for the responses. 

 

Jim, I tested the can between the blower motor and the STV just as you suggested. The can works perfectly. 

 

I also went on the Old Air website and found two vacuum actuators that might fill the bill:

https://www.oldairproducts.com/product/23-5965-vacuum-actuator

https://www.oldairproducts.com/product/23-5960-vacuum-actuator

Is one of these the proper actuator for my application?

Tom

 

 

Tom, 

 

Here is the correct one. This is also the same one you would use on the firewall when and if needed. Follow Jim's advice on the replacement. I did this on my 63 several years ago. No problems and works great. Old Air Products also sells color coded vacuum lines. I also used these. 

 

23-5905 - Actuator | 1963-1979 GM Applications, Dual Port (oldairproducts.com)

 

Bill

[Jim Cannon]

There you go!

 

Remember to use a T-fitting to apply vacuum for "fully open" to both nipples. Then plug the other vacuum hose (the partial recirc line) with a golf tee.

[ytr1903]

The correct actuator has been ordered. 

Thanks for the help.

Tom

[XframeFX]

9 hours ago, Jim Cannon said:

There you go!

Applies to me too. I've been following this, thank-you.

 

This is on my List as well but will take a while for it to work its way up after resolving more pressing issues (Canada may have 5 weeks where AC would be nice - LOL).

I will check those vacuum actuators, replace and order colour stripped vacuum hoses.

 

The way I see it, 1st Gen AC is 2-parts: 1) Components related to the refrigerant and, 2) Controls (vacuum & levers)

[ytr1903]

In my very limited experience with Rivieras (this one), I have to admit that I agree with your conclusions. Refrigeration components and controls. The HVAC system seems way more complicated than it needs to be. 

The refrigeration components aspect, to me, is exacerbated by the fact that I want to keep Freon 12. I see the process of getting the AC running as a one time shot considering the cost of the freon and its scarcity, so, I want all my ducks in a row before the freon goes in. Hopefully, I won't try the patience of the other members here with my questions. 

 

Tom

[telriv]

To test the system BEFORE adding Freon consider using dry nitrogen. Less costly & can apply the same or more pressure for checking for leaks & will  not do any harm as long as it's evacuated out properly.

 

Tom T.

[1965rivgs]

11 hours ago, XframeFX said:

 

 

 

The way I see it, 1st Gen AC is 2-parts: 1) Components related to the refrigerant and, 2) Controls (vacuum & levers)

  That is correct, the system is comprised of two parts, the refrigeration system and the air handling/blower control system. Both must be functional to achieve proper operation.

Tom Mooney

[1965rivgs]

21 hours ago, Jim Cannon said:

There you go!

 

Remember to use a T-fitting to apply vacuum for "fully open" to both nipples. Then plug the other vacuum hose (the partial recirc line) with a golf tee.

Hi Jim

 

  I dont have a '63 vacuum schematic to reference but why would one only use a single vacuum nipple on a dual nipple actuator if both vacuum lines are available?

 

Tom

[Jim Cannon]

2 hours ago, 1965rivgs said:

Hi Jim

 

  I dont have a '63 vacuum schematic to reference but why would one only use a single vacuum nipple on a dual nipple actuator if both vacuum lines are available?

 

Tom

Yes!  Good question!  You connect one hose to both nipples with a t-fitting and plug the other hose.

 

It is a quirk of how the original stacked diaphragms worked with each other, compared to how the 2-port unit works.

 

The stacked diaphragms will get vacuum applied to one can or the other, depending on if you want partial recirc (actuator pulls part way in) or full fresh air (fully pulled in). Only one vacuum hose gets vacuum at a time.

 

On the single actuator with 2 nipples, like you have on the firewall, you have to apply vacuum to both nipples at the same in order to get the actuator fully retracted.  This is not what you have down under the fan; you have vacuum on one or the other at a time.  So if you connect one vacuum hose to each nipple, the actuator will not retract fully.

 

Lots of detail there, but that's the reason.  It took me a lot of time studying the shop manual to figure this out.

 

Edited September 9, 2022 by Jim Cannon (see edit history)

[1965rivgs]

28 minutes ago, Jim Cannon said:

Yes!  Good question!  You connect one hose to both nipples with a t-fitting and plug the other hose.

 

It is a quirk of how the original stacked diaphragms worked with each other, compared to how the 2-port unit works.

 

The stacked diaphragms will get vacuum applied to one can or the other, depending on if you want partial recirc (actuator pulls part way in) or full fresh air (fully pulled in). Only one vacuum hose gets vacuum at a time.

 

On the single actuator with 2 nipples, like you have on the firewall, you have to apply vacuum to both nipples at the same in order to get the actuator fully retracted.  This is not what you have down under the fan; you have vacuum on one or the other at a time.  So if you connect one vacuum hose to each nipple, the actuator will not retract fully.

 

Lots of detail there, but that's the reason.  It took me a lot of time studying the shop manual to figure this out.

 

  I see...if I am understanding correctly it seems the way to go would be to use a single nipple actuator if they are reproduced. I would be surprised if they are not. MANY GM '60's products used the single nipple actuator for fresh air door actuation in non AC applications.

  So by combining the two vacuum hoses into one and plugging the second one is losing the partial actuation function of the fresh air/ recirc door?

 

Tom

 

[XframeFX]

11 minutes ago, 1965rivgs said:

combining the two vacuum hoses into one and plugging the second one is losing the partial actuation function

Need a diagram and image of the actual actuator. Also, we're talking '63 here. For 1964 and up, similar?

[XframeFX]

A visual already reveals my vacuum modulator on top of my HVAC Levers is kaput. Replacements? Or, use the OldAir STV Kit which cycles the A6 Compressor clutch to temperature which would elimate the need for that vacuum modulator.

Edited September 9, 2022 by XframeFX (see edit history)

[Riviera63]

1 hour ago, Jim Cannon said:

Yes!  Good question!  You connect one hose to both nipples with a t-fitting and plug the other hose.

 

It is a quirk of how the original stacked diaphragms worked with each other, compared to how the 2-port unit works.

 

The stacked diaphragms will get vacuum applied to one can or the other, depending on if you want partial recirc (actuator pulls part way in) or full fresh air (fully pulled in). Only one vacuum hose gets vacuum at a time.

 

On the single actuator with 2 nipples, like you have on the firewall, you have to apply vacuum to both nipples at the same in order to get the actuator fully retracted.  This is not what you have down under the fan; you have vacuum on one or the other at a time.  So if you connect one vacuum hose to each nipple, the actuator will not retract fully.

 

Lots of detail there, but that's the reason.  It took me a lot of time studying the shop manual to figure this out.

 

Here are some pictures of what Jim is talking about.

 

Bill

 

P.S. As you can see in the 1st picture the existing connecting rod in the heater box has to be twisted slightly to hook up with the new vacuum actuator.

 

 

[Jim Cannon]

1 hour ago, 1965rivgs said:

  I see...if I am understanding correctly it seems the way to go would be to use a single nipple actuator if they are reproduced. I would be surprised if they are not. MANY GM '60's products used the single nipple actuator for fresh air door actuation in non AC applications.

  So by combining the two vacuum hoses into one and plugging the second one is losing the partial actuation function of the fresh air/ recirc door?

 

Tom

 

Yes, if we could find a single nipple actuator with the mounting studs spaced correctly, etc., then that would work.  Once I figured out that the one that goes on the firewall will also work here, I stopped hunting for the replacement.

 

Yes, the "fresh air/recirc door" now only has 2 positions: 100% fresh and 100% recirc.  We have gotten rid of the original "partial fresh -- partial recirc" position (which I never was too excited about).

 

 

[Jim Cannon]

14 minutes ago, Riviera63 said:

Here are some pictures of what Jim is talking about.

 

Bill

 

P.S. As you can see in the 1st picture the existing connecting rod in the heater box has to be twisted slightly to hook up with the new vacuum actuator.

 

 

Thank you for the pictures, Bill!

 

Worth 1,000 words.

 

I should also mention that there is a long spring up inside the recirc plenum that this vacuum diaphragm acts against.  The spring closes the door and the actuator opens it.

 

My return spring was broken.  I found a new spring of roughly the same strength at my local Ace Hardware and modified it a little to work.  You should investigate while everything is open.

 

I did all this with the fan motor off of the plenum, working through that hole, but with the plenum still mounted in the car.  Much easier to do if you have the plenum off anyway for other reasons.

 

 

[Jim Cannon]

1 hour ago, XframeFX said:

A visual already reveals my vacuum modulator on top of my HVAC Levers is kaput. Replacements? Or, use the OldAir STV Kit which cycles the A6 Compressor clutch to temperature which would eliminate the need for that vacuum modulator.

You can just disconnect and plug the vacuum hose to the STV and run it like that.   It will run the A/C evaporator at maximum cooling all the time (which is what I do anyway -- because max cooling is still not what we have become used to in modern cars).  The biggest downside is that it is easy to get the evaporator core to freeze up into a solid block of ice in humid locations.  Air flow through the evaporator stops and cooling is poor.

 

Or you can put in the STV replacement kit, which monitors the evaporator core temperature and cycles the compressor off when the core gets too cold.  Stops freeze up.  Good cooling all the time.

 

In either case, you will control your comfort in the car with the fan speed.  The temp knob on the A/C side of the control panel will do very little, except that when you push it all the way in to maximum cold and you have the fan on high (both knobs), the recirc door will close and you get 100% recirc. All other times you get 100% fresh air in. 

 

The STV approach was a bad design, as was "hot gas recirc" used in other large GM vehicles.  GM was still learning how to do automotive A/C right; lots of different ideas were developed.  Later systems are much better, where the evaporator is followed by a heater core to warm the cool dry air back up to your desired temperature.

[Jim Cannon]

1 hour ago, XframeFX said:

Need a diagram and image of the actual actuator. Also, we're talking '63 here. For 1964 and up, similar?

AFAIK, the '64 and '65 are the same.  I have not studied them in detail.

 

[Riviera63]

1 hour ago, Jim Cannon said:

Thank you for the pictures, Bill!

 

Worth 1,000 words.

 

I should also mention that there is a long spring up inside the recirc plenum that this vacuum diaphragm acts against.  The spring closes the door and the actuator opens it.

 

My return spring was broken.  I found a new spring of roughly the same strength at my local Ace Hardware and modified it a little to work.  You should investigate while everything is open.

 

I did all this with the fan motor off of the plenum, working through that hole, but with the plenum still mounted in the car.  Much easier to do if you have the plenum off anyway for other reasons.

 

 

 

Here is another 1000 word dose. Mine was broken. I found a good match in a variety pack of springs at my local NAPA. Some of you may have wondered what that hole on the top of the heater box is for. The spring hooks into that hole and then to the door inside. Don't assume that your spring is good because you can see the end of it still attached in that hole. My spring had broken inside the heater box. 

 

Bill

 

P.S. Here is what I found inside my heater box to hold that door open because of the broken spring. Someone drilled a hole in the top of the heater box and stuck this in. I thought at the time the top of the nail was a rivet and supposed to be there. When I redid things I put a chrome rivet that I had removed from my old kick panels. It is shiny and looks like it is supposed to be there.

 

 

Edited September 9, 2022 by Riviera63 (see edit history)

[Turbinator]

On 9/9/2022 at 12:40 PM, XframeFX said:

A visual already reveals my vacuum modulator on top of my HVAC Levers is kaput. Replacements? Or, use the OldAir STV Kit which cycles the A6 Compressor clutch to temperature which would elimate the need for that vacuum modulator.

In my 63 I have the STV by pass kit. Works so the vacuum modular is not necessary. The STV did not work for me. I stayed with R12.