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Replacing air conditioner system


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I have a 70 Monte with factory air. Most of the system is here except the front hose off the compressor. I'm looking for advice on going back to original set up or Vintage Air? Any advice would be appreciated. Thanks.

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It depends on a lot of factors Dale, with a bunch of different paths to take (and there will be multiple opinions on that too, lol).

That being said, there are a couple things to consider first. Has the system ever worked or did you get the car with that missing front hose? Is the original type GM A6 compressor there? Do you want to charge the system with the old R12 refrigerant, or go with the more readily available R134A? Are you concerned about original appearance. How much is cost a factor?

 - The original compressors were large, heavy, inefficient, and prone to seal leakage.

- If the system has been open for any length of time, it'll need a new filter/drier, and a system flush would be recommended as well. I'd try to see if the compressor even turns before wasting time going thru the system, to later find out it's defective anyways (and it could still be a leaker).

Personally, I'm not a fan of the Vintage air conversions, especially if the car was a factory A/C car to start with. As long as the original dash controls & actuators work good, everything else in the system can be made to work with readily available replacement parts, as well as R134A upgrade kits.

The Sanden type of replacement/upgrade compressors are smaller, more efficient, and don't leak like the old A6's, though they obviously don't look stock. There are 'S6' compressors that bolt in place of the originals, but have Sanden type internals. They are a bit expensive though, but can be painted black to mimic a factory type installation if that's your goal.

The whole thing can snowball from there. R134A isn't as efficient as R12 at making cold air, plus the molecule is smaller, making replacement hose selection a factor. R134 hoses are a 'Barrier' type, with an internal liner of sorts, that helps keep the smaller refrigerant molecule inside the system. Popular opinion is that good, used R12 system hoses are OK to re-use as the old oil in the system coated the inside, helping to create a bit of a sealing effect. Oh, it's recommended to replace all of the system O-rings to 134a spec materials too. The refrigerant oil is different too, necessitating a system flush as well.

R134a replacement evaporators & condensers tend to be a 'parallel flow' type, which is more efficient at heat transfer than the old originals. I've converted systems with the old components, and systems with the new parts and can say the new ones seem to make for colder measured air temperatures coming out of the vents. It obviously comes at a cost though. Labor is another factor, would you be doing the work yourself, or farming it out?

I tend to like the stuff that 'Original Air' group has, plus have had great luck with their customer service. Others here like different vendors. If you're missing parts, or want to upgrade to the more efficient parts, their 'Upgrade' kits are complete with the better evaporators & condensers, fit good, and work great. They have 3 stages, all with varying degrees of parts & prices.

 

Stage1 with compressor, hoses, filter/drier:

https://www.originalair.com/69-72-chevelle-el-camino-malibu-monte-carlo-sprint-134a-rotary-compressor-upgrade-kit-stage-1

 

Stage 2 and 3 are available with more parts (they're not showing a Stage 2 for Monte that's $200 cheaper, which deletes the evaporator, but call them and they'll make it up if that's your choice). Stage 3 is the best they offer, are complete, and work well. For the extra $200, that's my choice, though it's extra work to replace the evaporator. My motto, do it right, do it once and be done with it... :

https://www.originalair.com/70-72-monte-carlo-ultimate-engine-compartment-upgrade-kit-134a

 

Here is the S6 compressor I spoke of, that looks stock. It can also be had in black:

https://www.originalair.com/s6-compressor-new

Parts:

https://www.originalair.com/replacement-parts

 

Hopefully, this gives you some info and direction. If you have questions, just ask, or PM me your phone number and I can explain things in more detail. This is just a small bit of info regarding a conversion, there are plenty of other factors, and tips necessary to make a good installation.

 

EDIT: I forgot, they do have 'Stock' replacement kits too, with the A6 compressors. Appears to be the same prices, but still with the leak prone, heavy, horse power robbing compressor. Still, it would be a good choice for the purist type of owner.

https://www.originalair.com/70-72-monte-carlo-ac-compressor-replacement-parts-kit-v8-stage-1-exc-1970-with-bbc-2

https://www.originalair.com/70-72-monte-carlo-ac-replacement-parts-kit-v8-stage-2

https://www.originalair.com/70-72-monte-carlo-ac-replacement-parts-kit-v8-stage-3

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Thanks for all the info. Very informative! I do we want to do it right and be done with it. I recently purchased the car and trying to fix all the issues. I really appreciate your expertise and knowledge.

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Well said Joe!!!. There’s a multitude of variables… my 71 has original style compressor but has been converted to R134 , And does well.. did not replace hoses so I  have to keep tabs on Freon pressure about once a year.. much better than trying to find R 12 here tho… 

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On 3/30/2024 at 3:15 AM, jft69z said:

It depends on a lot of factors Dale, with a bunch of different paths to take (and there will be multiple opinions on that too, lol).

That being said, there are a couple things to consider first. Has the system ever worked or did you get the car with that missing front hose? Is the original type GM A6 compressor there? Do you want to charge the system with the old R12 refrigerant, or go with the more readily available R134A? Are you concerned about original appearance. How much is cost a factor?

 - The original compressors were large, heavy, inefficient, and prone to seal leakage.

- If the system has been open for any length of time, it'll need a new filter/drier, and a system flush would be recommended as well. I'd try to see if the compressor even turns before wasting time going thru the system, to later find out it's defective anyways (and it could still be a leaker).

Personally, I'm not a fan of the Vintage air conversions, especially if the car was a factory A/C car to start with. As long as the original dash controls & actuators work good, everything else in the system can be made to work with readily available replacement parts, as well as R134A upgrade kits.

The Sanden type of replacement/upgrade compressors are smaller, more efficient, and don't leak like the old A6's, though they obviously don't look stock. There are 'S6' compressors that bolt in place of the originals, but have Sanden type internals. They are a bit expensive though, but can be painted black to mimic a factory type installation if that's your goal.

The whole thing can snowball from there. R134A isn't as efficient as R12 at making cold air, plus the molecule is smaller, making replacement hose selection a factor. R134 hoses are a 'Barrier' type, with an internal liner of sorts, that helps keep the smaller refrigerant molecule inside the system. Popular opinion is that good, used R12 system hoses are OK to re-use as the old oil in the system coated the inside, helping to create a bit of a sealing effect. Oh, it's recommended to replace all of the system O-rings to 134a spec materials too. The refrigerant oil is different too, necessitating a system flush as well.

R134a replacement evaporators & condensers tend to be a 'parallel flow' type, which is more efficient at heat transfer than the old originals. I've converted systems with the old components, and systems with the new parts and can say the new ones seem to make for colder measured air temperatures coming out of the vents. It obviously comes at a cost though. Labor is another factor, would you be doing the work yourself, or farming it out?

I tend to like the stuff that 'Original Air' group has, plus have had great luck with their customer service. Others here like different vendors. If you're missing parts, or want to upgrade to the more efficient parts, their 'Upgrade' kits are complete with the better evaporators & condensers, fit good, and work great. They have 3 stages, all with varying degrees of parts & prices.

 

Stage1 with compressor, hoses, filter/drier:

https://www.originalair.com/69-72-chevelle-el-camino-malibu-monte-carlo-sprint-134a-rotary-compressor-upgrade-kit-stage-1

 

Stage 2 and 3 are available with more parts (they're not showing a Stage 2 for Monte that's $200 cheaper, which deletes the evaporator, but call them and they'll make it up if that's your choice). Stage 3 is the best they offer, are complete, and work well. For the extra $200, that's my choice, though it's extra work to replace the evaporator. My motto, do it right, do it once and be done with it... :

https://www.originalair.com/70-72-monte-carlo-ultimate-engine-compartment-upgrade-kit-134a

 

Here is the S6 compressor I spoke of, that looks stock. It can also be had in black:

https://www.originalair.com/s6-compressor-new

Parts:

https://www.originalair.com/replacement-parts

 

Hopefully, this gives you some info and direction. If you have questions, just ask, or PM me your phone number and I can explain things in more detail. This is just a small bit of info regarding a conversion, there are plenty of other factors, and tips necessary to make a good installation.

 

EDIT: I forgot, they do have 'Stock' replacement kits too, with the A6 compressors. Appears to be the same prices, but still with the leak prone, heavy, horse power robbing compressor. Still, it would be a good choice for the purist type of owner.

https://www.originalair.com/70-72-monte-carlo-ac-compressor-replacement-parts-kit-v8-stage-1-exc-1970-with-bbc-2

https://www.originalair.com/70-72-monte-carlo-ac-replacement-parts-kit-v8-stage-2

https://www.originalair.com/70-72-monte-carlo-ac-replacement-parts-kit-v8-stage-3

Thanks for the advice!  I decided to go with stage 3 of Original Air. I  plan on installing the parts myself and it seems the condenser is a bear!

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9 minutes ago, my 7d dream said:

Thanks for the advice!  I decided to go with stage 3 of Original Air. I  plan on installing the parts myself and it seems the condenser is a bear!

That's a very good choice Dale. I'll PM you my phone number, there's plenty more info that may help you, especially if you're doing it yourself.

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What are some tell tail signs that a system has been converted? Mine still has the A6 compressor, but it appears the filter-drier has been changed.

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15 minutes ago, Marks71 said:

What are some tell tail signs that a system has been converted? Mine still has the A6 compressor, but it appears the filter-drier has been changed.

Tough to say, especially if they didn't leave a 'conversion sticker' someplace. Check the high and low gauge access points, do they have adapters put on there to accept R134A connections? That would be my first place to look. Next would be if the POA valve was replaced with a cycling switch maybe.

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6 hours ago, jft69z said:

Tough to say, especially if they didn't leave a 'conversion sticker' someplace. Check the high and low gauge access points, do they have adapters put on there to accept R134A connections? That would be my first place to look. Next would be if the POA valve was replaced with a cycling switch maybe.

Ive heard both sides about this and I'm NO mechanic......But was told you can add R134A to the old system. I'm sure someone more knowledgaeable will comment/update this scenario.

DISCLAIMER....... maybe I was told this because I don't run my a/c, I just wanted to test the system after the engine swap to make sure everything was working properly. I bought the adapter kit, charged and tested the system, all ok. Haven't used it since. I removed the fittings to keep the stock look 😮

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13 hours ago, DragCat said:

Ive heard both sides about this and I'm NO mechanic......But was told you can add R134A to the old system. I'm sure someone more knowledgaeable will comment/update this scenario.

DISCLAIMER....... maybe I was told this because I don't run my a/c, I just wanted to test the system after the engine swap to make sure everything was working properly. I bought the adapter kit, charged and tested the system, all ok. Haven't used it since. I removed the fittings to keep the stock look 😮

You can't simply mix R12 and R134a refrigerant. So, don't add refrigerant without knowing what is in the system, or if it has been converted. There are refrigerant identification analyzers out there, but they're very expensive. About as expensive as replacing your entire A/C system because you didn't service it properly.

Besides the fact the refrigerants have different chemical properties, the lubricants are entirely different and could also lead to destruction and expensive repairs.

Here's some info, straight from a refrigerant manufacturer. Look at the parts regarding compatibility of refrigerants, lubricants, and seal materials. Doesn't exactly paint a pretty picture.

https://www.general-refrigeration.gr/images/eshop/catalog/products/0454/files/R134a information.pdf

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