Red Riviera Bob

63 Riviera AC vent doors opening and closing

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 Old Air Products sells an STV (suction throttle valve) eliminator kit.  This replace the STV and incorporates a cycling compressor like modern systems. $165.  

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1 hour ago, RivNut said:

That's the way all modern systems work.  Your A6 compressor is very tough and reliable.  I know many folks who've made this adaptation and are very happy with it.

Modern cars have fuel injection and disc brakes, too.  ;) 

 

IMHO, a binary system (full cold or off) isn't much of a system.  That's like having cruise control that's either full throttle or idle.

Edited by KongaMan (see edit history)

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You're familiar with the concept. Hold the temp until it drops a little, then the compressor kicks on and cools it down again.  You're home's HVAC system. Unless you're still stoking an old coal furnace and have one of those big units in a window which blows air across a pool of water from your garden hose.

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Undid the crimps on both of the diaphragms. The bottom membrane is torn and I think I could replace. The top diaphragm looks OK but there is a grommet/seal at the bottom hole that is shot. looks like some sort of a special seal.  I will order the diaphragm  from Old Air Products.

DSCN2136.JPG

Edited by Chasander
added pic (see edit history)

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On 8/6/2017 at 10:39 AM, 1965rivgs said:

Low volume from the AC registers is generally attributable to the vacuum actuator located at the upper pass side of the firewall. There should be mechanical linkage which is exposed enabling you to judge whether the vacuum can is pulling it all the way to the limit of its travel. If not, one can physically pull the linkage toward the can and block it there to direct full blower volume to the AC registers.

If the can is not performing properly it could be due to low vacuum or the can is bad. Both possibilities are very common. I would suggest simply replacing it rather than trying to "rebuild" it. We are fortunate a replacement is available!

Keep in mind there can be other causes for low volume like air leaks in the post blower system. Hope this helps,

 

  Tom

 

PS The original systems can blow ice cold, ie 36 degrees F at the pass AC vent, but if using R134 results will be less. In addition to the efficiency of the AC refrigerant system one must consider whether the cabin is well sealed. The first gen Rivs leak air profusely so good weatherstripping and sealing at the frameless glass interfaces is very important to keep cabin temps low enough to be comfortable in challenging conditions.

Tom, when you say " upper pass sideof the firewall" could the location be under hood on the passenger side of the car? The " can" , is this the vacuum Actuator? If so, I be pulled the mechanical linkage and it is very very hard to move. It is hard for me to be believe there is enough vacuum from the Actuator to move anything. One of my friends were trying to get some volume of air moving some way or another. I was in the cabin and he pushed and pulled on the vacuum Actuator linkage while taking off a vacuum hose to the Actuator,  I got enough air volume equal to a hurricane. 

I bought some a vacuum hose kit because the hoses looked awful weak. The mechanic that did the AC compressor, drier, evacuate the old AC R12 gas and did get the cold air working said I needed a #1 vacuum switch AC control part # 1194602. Actually the mechanic pointed to the switch and said you need one of those switches. The mechanic didn't say anything about the Actuator or hoses. Now, I left the shop paying for 8 hours labor and a diagnostic fee. I had cold air, but I couldn't get the cold air in the cabin. I have no beef paying for the work that was completed, but don't you think I should have been given some direction for next steps  to get the air in the cabin?

In summary, you are suggesting a new vacuum Actuator could improve the operation ? Old Air has one for $52.00.

all I've got to do is to get the vents working, the cold air is there. Thanks again for your help.

Red Riviera Bob

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The problem here is not that you don't have cold air, but that you don't have it coming out of the vents, correct?  Did you test the actuator to see if it holds vacuum?  You should be able to generate enough vacuum with your lungs to operate the diaphragm.  Failing that, a MightyVac can come in handy for lots of things on these cars.  Irrespective of the vacuum source, can you get the thing to move like it should?

 

Remember, the actuator is working against a spring when it pulls the door.  The spring shouldn't be that strong, but there's a chance that the door pivots could use a little lube.  And face it, just about every moving part inside the blower box could probably benefit from from being cleaned and lubed after 50 years.  You probably don't want to hear (or do) this, but pulling the blower box and lubing everything inside (motor, fan, linkage, etc.) wouldn't be the dumbest thing you ever did to your car.

 

All of this is to say that you can't identify a solution until you've identified the problem.  Incorrect air flow is a symptom.  While that usually indicates a problem with the actuator, that's not always the case.  For example, you might have a leak in the vacuum line.  Do you have a vacuum gauge?  (Again, the MightyVac could be real helpful.)  Put the gauge on each of the two lines, then wiggle the lines to see if you get a steady reading.  It's not unusual for a line to split or melt.  As suggested, the problem could be the vacuum switch.  If it leaks, you won't be getting full vacuum at the actuator.  You really need to find what's which component isn't working correctly rather than throwing parts and money at it until you guess right.

 

In the meantime, if you really want that air to come out of the vents, pull the linkage out out all the way and clamp a small pair of vice grips on it so it can't retract. ;)

 

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6 hours ago, Red Riviera Bob said:

Tom, when you say " upper pass sideof the firewall" could the location be under hood on the passenger side of the car? The " can" , is this the vacuum Actuator? If so, I be pulled the mechanical linkage and it is very very hard to move. It is hard for me to be believe there is enough vacuum from the Actuator to move anything. One of my friends were trying to get some volume of air moving some way or another. I was in the cabin and he pushed and pulled on the vacuum Actuator linkage while taking off a vacuum hose to the Actuator,  I got enough air volume equal to a hurricane. 

I bought some a vacuum hose kit because the hoses looked awful weak. The mechanic that did the AC compressor, drier, evacuate the old AC R12 gas and did get the cold air working said I needed a #1 vacuum switch AC control part # 1194602. Actually the mechanic pointed to the switch and said you need one of those switches. The mechanic didn't say anything about the Actuator or hoses. Now, I left the shop paying for 8 hours labor and a diagnostic fee. I had cold air, but I couldn't get the cold air in the cabin. I have no beef paying for the work that was completed, but don't you think I should have been given some direction for next steps  to get the air in the cabin?

In summary, you are suggesting a new vacuum Actuator could improve the operation ? Old Air has one for $52.00.

all I've got to do is to get the vents working, the cold air is there. Thanks again for your help.

Red Riviera Bob

Hi Bob,

  Yes, that is the actuator and location I was referring to.

Obviously the door/linkage should be free enough for the actuator to do its job.

You could try disconnecting the linkage from the actuator and see if the actuator is retracting when it should. These are almost always bad or work intermittently but who knows, you may get lucky.

As I and others have stated you can force/hold the linkage in the AC position as a temporary repair.

  Tom

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2 hours ago, 1965rivgs said:

Hi Bob,

  Yes, that is the actuator and location I was referring to.

Obviously the door/linkage should be free enough for the actuator to do its job.

You could try disconnecting the linkage from the actuator and see if the actuator is retracting when it should. These are almost always bad or work intermittently but who knows, you may get lucky.

As I and others have stated you can force/hold the linkage in the AC position as a temporary repair.

  Tom

Tom, I be had the 63 for over a year. The good thing about the car is not much at all had been maintained nor molested. I've had to rebuild carb and brake booster. My list of deferred maintenance updates and preventive maintenance items  could go on and on. Thank you for the help on the vacuum actuator. I'll order the actuator today. In the meantime I'll initiate the temp fix on the actuator.

thanks again

Red Riviera Bob

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8 hours ago, KongaMan said:

The problem here is not that you don't have cold air, but that you don't have it coming out of the vents, correct?  Did you test the actuator to see if it holds vacuum?  You should be able to generate enough vacuum with your lungs to operate the diaphragm.  Failing that, a MightyVac can come in handy for lots of things on these cars.  Irrespective of the vacuum source, can you get the thing to move like it should?

 

Remember, the actuator is working against a spring when it pulls the door.  The spring shouldn't be that strong, but there's a chance that the door pivots could use a little lube.  And face it, just about every moving part inside the blower box could probably benefit from from being cleaned and lubed after 50 years.  You probably don't want to hear (or do) this, but pulling the blower box and lubing everything inside (motor, fan, linkage, etc.) wouldn't be the dumbest thing you ever did to your car.

 

All of this is to say that you can't identify a solution until you've identified the problem.  Incorrect air flow is a symptom.  While that usually indicates a problem with the actuator, that's not always the case.  For example, you might have a leak in the vacuum line.  Do you have a vacuum gauge?  (Again, the MightyVac could be real helpful.)  Put the gauge on each of the two lines, then wiggle the lines to see if you get a steady reading.  It's not unusual for a line to split or melt.  As suggested, the problem could be the vacuum switch.  If it leaks, you won't be getting full vacuum at the actuator.  You really need to find what's which component isn't working correctly rather than throwing parts and money at it until you guess right.

 

In the meantime, if you really want that air to come out of the vents, pull the linkage out out all the way and clamp a small pair of vice grips on it so it can't retract. ;)

 

Mr. Konga Man, your directions are understood and appreciated. Yes, you are right on with digging and finding the root of the problem. Throwing $ away needlessly goes against my grain.

Lubricating hinges and cables inside the blower box is something I can do. I'm a big fan of proper lubrication on mechanical parts that perform work. When you mentioned " Mighty Vac" I thought you meant a brand name vacuum cleaner. I believe the Might Vac is a tool I can use to track vacuum pressure. I'll check it out. I'd hate to buy a new actuator and vacuum switch ( which I already have on order) and find the AC still doesn't work. I'm not mechanical, but my persistence and resilience in such efforts takes me a long way.

thank you again for your help,

Red Riviera Bob

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On 8/2/2017 at 6:43 PM, 1965rivgs said:

Be sure there is a vacuum check valve in the vacuum feed line. Otherwise, when engine vacuum is low, as in medium to heavy acceleration, the vacuum in the HVAC system can bleed back into the intake manifold and cause issues with the HVAC doors. There is a factory check valve at the intake manifold but they are often bad.

Having stated the above ANY vacuum leak in the system can cause overall vacuum level to be low and affect other areas/components in the system.

  Tom Mooney

Tom,I took the brass check valve at the intake manifold and cleaned it with carb cleaner and 000 steel wool. The little washer must be vulcanized because I did not manage to loose it, the spring on the little thing on the end of the spring. I ordered a Mighty Vac vacuum pressure kit so I'll have to wait until I get that tool to see if the check valve is any good or not. I'm in high hopes with a friend helping me ( who is a 40+ year veteran mechanic ) the vacuum system will get straightened out before the end of October. I;d like to use it once or twice before cool weather.

Thanks again.

RRB

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Did you disassemble it?  It's been a loooooooong time but if I remember correctly, you can take it apart and inspect each part.  Seems to me I remember a stainless ball, and a spring that make up the check valve. But as I said, it's been a looooooooong time.  I could ever thinking of so e thing entirely different.

Edited by RivNut (see edit history)

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Again, folks, all you need for a quick check of these diaphragms, switches, and valves is a piece of hose and your lungs.  You can easily generate enough vacuum to test and operate any of these components.  Don't make it harder than it needs to be.

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On 8/13/2017 at 6:34 PM, RivNut said:

Did you disassemble it?  It's been a loooooooong time but if I remember correctly, you can take it apart and inspect each part.  Seems to me I remember a stainless ball, and a spring that make up the check valve. But as I said, it's been a looooooooong time.  I could ever thinking of so e thing entirely different.

Ed, I took it apart and cleaned it up. At the end of a spring is a fitting that seats on top of the rubber ring. The fitting younand are ai referring is not a ball. After I put the brass check valve back together and tested it would not hold a vacuum. I bought a check valve from Cold Air. It appears as though the AC project is making progress. Half of the job is completed as I have cold air. The second part of the job is to get the cold in the cabin at an acceptable volume. Stay tuned.

RRB

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On 8/9/2017 at 10:59 PM, Red Riviera Bob said:

Tom, when you say " upper pass sideof the firewall" could the location be under hood on the passenger side of the car? The " can" , is this the vacuum Actuator? If so, I be pulled the mechanical linkage and it is very very hard to move. It is hard for me to be believe there is enough vacuum from the Actuator to move anything. One of my friends were trying to get some volume of air moving some way or another. I was in the cabin and he pushed and pulled on the vacuum Actuator linkage while taking off a vacuum hose to the Actuator,  I got enough air volume equal to a hurricane. 

I bought some a vacuum hose kit because the hoses looked awful weak. The mechanic that did the AC compressor, drier, evacuate the old AC R12 gas and did get the cold air working said I needed a #1 vacuum switch AC control part # 1194602. Actually the mechanic pointed to the switch and said you need one of those switches. The mechanic didn't say anything about the Actuator or hoses. Now, I left the shop paying for 8 hours labor and a diagnostic fee. I had cold air, but I couldn't get the cold air in the cabin. I have no beef paying for the work that was completed, but don't you think I should have been given some direction for next steps  to get the air in the cabin?

In summary, you are suggesting a new vacuum Actuator could improve the operation ? Old Air has one for $52.00.

all I've got to do is to get the vents working, the cold air is there. Thanks again for your help.

Red Riviera Bob

 

 

Bob, 

 

Thank you for starting this thread. Reading this has helped me solve the problem I have had with my AC since I purchased my car. I too, had the same problem. Cold air, you could hear the blower fan going for all it was worth but,  low air flow at the AC vents in the car.  The maddening thing is that it would blow fine once in a great while. I went through and did several things that in hindsight were all good to do but, did not solve my problem. Including but not limited to replacing the #@%!*&! double diaphragm which was shot and removing the blower/heater box to replace the spring in there. I was fortunate to have small hands as I don't know how I would have gotten a couple of those screws out or back in on that heater box without a hoist to put the car on. This post that you and Tom were going back and forth on set me on the path to getting my car cooling the way it should. I just finished replacing the passenger side vacuum actuator on my car a half an hour ago. Problem solved! Powerful air flow out of all AC vents. Of course, now it probably won't get hot again until next summer. Here's hoping for hot weather for the trip to the ROA convention in Overland Park, KS next year. This is gives me a great sense of relief and accomplishment. This may not seem like much to the guys that know these cars and are mechanics but, for the "shade tree" mechanic it doesn't get any better than this. In my doing this replacement I ended up dealing with the #1, #2 and #3 vacuum switches because I did some vacuum line replacement. I talked to Jim Cannon about these. You should check all 3 to make sure that the plungers move freely. The grease hardens and they get sticky after all of these years. Spray some silicone in the vacuum ports and move the plungers back and forth to get them moving freely. Do not use WD 40. It may be that yours was just stuck. You can also put vacuum on the ports by mouth or with a vacuum tool to see if they work when you move the plungers. I had a couple that were pretty sticky. They are pretty easy to get to and remove. I hope you get to the bottom of your problems soon and thanks for indirectly helping me solve mine.

 

Bill

 

 

IMG_2997.JPG

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Bill,

 

Your setup looks just like mine (only cleaner ;) ). It looks like you've converted to R134A. What kind of temperatures do you see at the vents? 

 

BTW, where is that vacuum actuator on a 63?

 

And congrats on the fix.  IMHO, sorting out HVAC vacuum issues is one of the most frustrating jobs on these cars.

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23 minutes ago, KongaMan said:

Bill,

 

Your setup looks just like mine (only cleaner ;) ). It looks like you've converted to R134A. What kind of temperatures do you see at the vents? 

 

BTW, where is that vacuum actuator on a 63?

 

And congrats on the fix.  IMHO, sorting out HVAC vacuum issues is one of the most frustrating jobs on these cars.

 

 

Yes, it was converted to R134A and also has a cycling switch. I'm not sure exactly what the temp is at the vents. I know the guys that work on my car checked it once and if I remember correctly it was in the 40's. They seemed to think it was fine. I am anxious to try it out and see how it does with good air flow. 

 

The vacuum actuator is next to the blower motor and to the left of the STV (or what's left of it).

 

Thanks for the pat on the back. I have had this car for 4 years now and I remember my first look at all of those vacuum hoses, the inside of the heater/AC control box on the fender and thought OMG what is this? I will never understand this mess! It was like looking at a book written in Chinese. Now that I have done some things with the HVAC system I think I have a good basic understanding of it works and it is not nearly as daunting as it once seemed. I'm not afraid of it anymore. It's been a lot of fun learning and doing new things to my car and seeing positive results. 

 

Bill

 

 

IMG_2998.JPG

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18 minutes ago, Riviera63 said:

Yes, it was converted to R134A and also has a cycling switch. I'm not sure exactly what the temp is at the vents. I know the guys that work on my car checked it once and if I remember correctly it was in the 40's. They seemed to think it was fine. I am anxious to try it out and see how it does with good air flow.

 

In the 40s should be good.  It would be interesting to know what the high and low side pressures are -- although bypassing the STV may affect that somewhat.

 

19 minutes ago, Riviera63 said:

The vacuum actuator is next to the blower motor and to the left of the STV (or what's left of it).

 

What we have here is a brain cramp. ;) You wrote "actuator" and I was thinking "modulator" -- which is a different part entirely.  You didn't happen to encounter the modulator in your travels, did you?

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1 hour ago, Riviera63 said:

 

 

Bob, 

 

Thank you for starting this thread. Reading this has helped me solve the problem I have had with my AC since I purchased my car. I too, had the same problem. Cold air, you could hear the blower fan going for all it was worth but,  low air flow at the AC vents in the car.  The maddening thing is that it would blow fine once in a great while. I went through and did several things that in hindsight were all good to do but, did not solve my problem. Including but not limited to replacing the #@%!*&! double diaphragm which was shot and removing the blower/heater box to replace the spring in there. I was fortunate to have small hands as I don't know how I would have gotten a couple of those screws out or back in on that heater box without a hoist to put the car on. This post that you and Tom were going back and forth on set me on the path to getting my car cooling the way it should. I just finished replacing the passenger side vacuum actuator on my car a half an hour ago. Problem solved! Powerful air flow out of all AC vents. Of course, now it probably won't get hot again until next summer. Here's hoping for hot weather for the trip to the ROA convention in Overland Park, KS next year. This is gives me a great sense of relief and accomplishment. This may not seem like much to the guys that know these cars and are mechanics but, for the "shade tree" mechanic it doesn't get any better than this. In my doing this replacement I ended up dealing with the #1, #2 and #3 vacuum switches because I did some vacuum line replacement. I talked to Jim Cannon about these. You should check all 3 to make sure that the plungers move freely. The grease hardens and they get sticky after all of these years. Spray some silicone in the vacuum ports and move the plungers back and forth to get them moving freely. Do not use WD 40. It may be that yours was just stuck. You can also put vacuum on the ports by mouth or with a vacuum tool to see if they work when you move the plungers. I had a couple that were pretty sticky. They are pretty easy to get to and remove. I hope you get to the bottom of your problems soon and thanks for indirectly helping me solve mine.

 

Bill

 

 

IMG_2997.JPG

Bill, we are pretty much in the same boat regarding our air conditioning. I'm happy to learn you have the volume of air you want. Additionally, any info you can pick up on a thread that helps I'll vote for everytime. I understand you converted to the 134 A and you updated the STV ? Your temperature at 40 degrees coming out of the vents is cold enough for you then that is the right temperature. I've heard by word of mouth " spec" is suppose to be in the 30''s? I really don't know. I think my temp coming out of the vent was/is too low b/c the hoses freeze once in awhile. The hose doesn't freeze up but it gets ice on both ends.

I have a friend mechanic who is taking on the vacuum challenge. He Has narrowed down the vacuum leaks and we are in hopes of having a tight as humanly and mechanically possible. I stayed with the R12 and had the STV rebuilt by cold Air. Replacing the drier, muffler, A6 compressor, hoses(s), the R12 is pricey as well can add up. Oh, I bought the #1 vacuum Actuator switch and the  same vacuum Actuator you replaced as well. I have to buy the double diaphragm as well. Where did you buy your double diaphragm? 

We are closing in the AC challenge repair. My friend is doing the work. I assist by getting the parts and doing the step and fetch while he cusses at the system. I'm not close to being a shade tree mechanic, but some projects I can handle I'll go ahead and give it a go. There are other things I can hold my own, but auto mechanics is not my strong suite.

thanks for the tip on the sticky vacuum switches as they are scarce and when you do find a switch the price of the switch gets your attention.

RRB

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26 minutes ago, KongaMan said:

 

In the 40s should be good.  It would be interesting to know what the high and low side pressures are -- although bypassing the STV may affect that somewhat.

 

 

What we have here is a brain cramp. ;) You wrote "actuator" and I was thinking "modulator" -- which is a different part entirely.  You didn't happen to encounter the modulator in your travels, did you?

 

I don't know. I have no idea what a modulator is. Describe it to me and I'll see if I have one and where it's located. Thanks.

 

Bill

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Quote "Oh, I bought the #1 vacuum Actuator switch and the  same vacuum Actuator you replaced as well. I have to buy the double diaphragm as well. Where did you buy your double diaphragm? "

 

Go back and read post #11

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24 minutes ago, Red Riviera Bob said:

Bill, we are pretty much in the same boat regarding our air conditioning. I'm happy to learn you have the volume of air you want. Additionally, any info you can pick up on a thread that helps I'll vote for everytime. I understand you converted to the 134 A and you updated the STV ? Your temperature at 40 degrees coming out of the vents is cold enough for you then that is the right temperature. I've heard by word of mouth " spec" is suppose to be in the 30''s? I really don't know. I think my temp coming out of the vent was/is too low b/c the hoses freeze once in awhile. The hose doesn't freeze up but it gets ice on both ends.

I have a friend mechanic who is taking on the vacuum challenge. He Has narrowed down the vacuum leaks and we are in hopes of having a tight as humanly and mechanically possible. I stayed with the R12 and had the STV rebuilt by cold Air. Replacing the drier, muffler, A6 compressor, hoses(s), the R12 is pricey as well can add up. Oh, I bought the #1 vacuum Actuator switch and the  same vacuum Actuator you replaced as well. I have to buy the double diaphragm as well. Where did you buy your double diaphragm? 

We are closing in the AC challenge repair. My friend is doing the work. I assist by getting the parts and doing the step and fetch while he cusses at the system. I'm not close to being a shade tree mechanic, but some projects I can handle I'll go ahead and give it a go. There are other things I can hold my own, but auto mechanics is not my strong suite.

thanks for the tip on the sticky vacuum switches as they are scarce and when you do find a switch the price of the switch gets your attention.

RRB

 

Bob,

 

The air was converted before I bought the car. The STV is not used in this conversion. It looks like it is there but, the inner workings are gone. The cycling switch was added after I had the car when it was getting a new heater core and radiator. I had the guy also check over the air as well. I can't even pretend to understand all of these things. I believe the cycling switch was added because the STV was inoperative. 

 

The same diaphragm you got for the passenger side is the same diaphragm you use to replace the double diaphragm because those are no longer available. That conversion is discussed in other threads. Jim Cannon has commented on this in those threads. I followed his lead when I replaced mine.

 

Bill

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Ed, without too much fear I'll dare to be slow:

do I need  2 each of what is described from Classic Buick parts? There are two pics in the catalogue. Is one pic the front and one pic the crack of the same diaphragm?

i get the item shown is the outside air diaphragm. Is the " recirculating air diaphragm" the same as in the picture?

I appreciate your patience and assistance.

RRB

 

 

 

 

 

 

Model application: Most A/C models as required for outside air inlet, defrost or diverter door. 4″ black plastic, 2 staggered-ports.GM #1998905 (1st type was white plastic & 63 Riviera 1st type lower was metal 2pc.) 63-65 Riviera uses 2 of these for upper and lower

 

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39 minutes ago, Red Riviera Bob said:

 

<snip>

 

I understand you converted to the 134 A and you updated the STV ? Your temperature at 40 degrees coming out of the vents is cold enough for you then that is the right temperature. I've heard by word of mouth " spec" is suppose to be in the 30''s? I really don't know. I think my temp coming out of the vent was/is too low b/c the hoses freeze once in awhile. The hose doesn't freeze up but it gets ice on both ends.

 

Guys, frost on the outside of your A/C hoses under the hood is normal and GOOD.  It means that your suction line is very cold, which is what you want.

 

Having your A/C only blow in the 40's on max while driving is not cold enough.  I see mid-30s with R-12 running down the road with it 110 degrees outside.  When it is humid in Houston, I get fog blowing out of my center vent.  That's cold!

 

This is the main complaint of people with R-134a, not cold enough.  If you have an STV, you can lower the suction pressure a few psi.

 

If you are going to run R-134a, you need a condenser in front of the radiator that was designed for R-134a.  The rest of the system does just fine.

 

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16 minutes ago, Riviera63 said:

 

Bob,

 

The air was converted before I bought the car. The STV is not used in this conversion. It looks like it is there but, the inner workings are gone. The cycling switch was added after I had the car when it was getting a new heater core and radiator. I had the guy also check over the air as well. I can't even pretend to understand all of these things. I believe the cycling switch was added because the STV was inoperative. 

 

The same diaphragm you got for the passenger side is the same diaphragm you use to replace the double diaphragm because those are no longer available. That conversion is discussed in other threads. Jim Cannon has commented on this in those threads. I followed his lead when I replaced mine.

 

Bill

Bill, I'm following you with your progress of what you have and what direction the AC was going when you got the car. I'm cool with that.

so, you bought two (2) vacuum actuators and converted them to work as the "double"?

thanks for your help.

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1 hour ago, Riviera63 said:

I don't know. I have no idea what a modulator is. Describe it to me and I'll see if I have one and where it's located. Thanks.

Never mind, I found it.  (It's part of the dash controls).

 

FYI, the modulator is the control for the STV.  The STV controls the evaporator pressure, which, in turn, controls the temperature.  Not sure how (or if) it would be used when the STV is replaced by a cycling switch.  If it's no longer used, it's just another potential source for a vacuum leak.

 

They may have changed this setup, but it used to be that there was no temperature control on your AC when you replaced the STV with a cycling switch.  That is, the AC was either on or off.  When it was on, the compressor was either running or it wasn't.  When it was running, you got full cold.  When it wasn't, you got uncooled outside air.  There was no "I want it a little bit warmer", as temperature adjustment was disabled when the STV was bypassed.  To use the home HVAC analogy that was offered earlier, it would be like saying that if you have the AC on, it's going to be 58° in the house; there is no thermostat.

Edited by KongaMan (see edit history)

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