I have a 72 fury
Converting to new Freon what does it take?
- Thread starter MBar
- Start date
First off, is the system intact, no loose or cut hoses etc. That makes the conversion a lot simpler. Put a socket on the clutch mount for the compressor, can you turn it two complete revolutions? If so the compressor has probably not failed. Next, you need to evacuate the system for about four hours to evaporate as much of the old R-12 oil as possible. Next, all of the old black O-Rings on the hose and valve connections need to be replaced with the modern high density green ones that are designed for use with R-134a. The low side hoses need to be replaced with barrier type hoses that are designed to be used with R-134a. The hook type fittings that were used on the low side hoses pierce the center membrane of the hoses, so they need to be replaced as well. Replace the filter dryer and the low pressure switch. Be sure to also install the appropriate R-134a service fittings. It would be a good idea to have the system flushed with dry Nitrogen to purge any remaining R-12 oil from the system. Next. evacuate the system for about a half and hour and see if it will hold vacuum when the service manifold valves have been closed and the vacuum pump has been turned off. If it holds steady vacuum for 5 minutes, the system is sound and not leaking. If it does not hold vacuum, you have a leak someplace that needs to be found and corrected. A lot of the time on systems that have been discharged for a long period of time, the front seal on the compressor has dried out and will cause a leak, so be aware of that possibility. Once you have the system to where it will hold vacuum, oil charge the system with 12-14 oz of Pag oil. This oil has a dispersant in it to keep any remaining R-12 oil from clumping or jelling. You can then recharge the system with R-134a and test run it.
If your system already has a dead RV2 compressor, you should seriously consider buying the retrofit kit for the Sanden rotary compressor as the RV2 compressors have a poor life expectancy running R-134a due to oil starvation issues. They are especially prone to failure on systems with dual evaporators. You will need to monitor the state of charge of your system on a regular basis as the R-134a gas molecule is smaller and lighter than R-12 and does not circulate the oil in the system as well. This makes the oil pool in the condenser, filter dryer and evaporator. If the system is not kept fully charged, the gas pressure drops, the oil stops circulating and the compressor dies.
Dave
rags
Senior Member
a retrofit kit. a set of gauges. a vacuum pump. a bottle of ester oil. three cans of cheapie refrigerant (walmart). an adapter for the cans. charge as necessary. if you have a sight glass, use it. make sure your fan clutch works to cool the high side (often overlooked, fan HAS to work! cowling, etc. has to be in place to pull heat from the condenser). do your self a huge favor: don't over complicate it. 134a in an intact stock r12 system will last last multiple seasons.
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As a follow up, these system are now approaching 50 years old. Care must be taken when removing fittings for the hoses etc, as they are often seized and can twist off the line to the condenser etc. If necessary use moderate heat to free the fittings.
Dave
Dave
If you need a condenser.....
ACCondenserStore.com | Car & HD Truck AC Condensers | A/C Condenser
I would replace the H-Block too if your system has one while you have it apart.
ACCondenserStore.com | Car & HD Truck AC Condensers | A/C Condenser
I would replace the H-Block too if your system has one while you have it apart.
I would also have your A/C hoses rebuilt while its apart. Fix it right the first time and never have to mess with it again.
I'm sure you have a hydraulic shop somewhere in California to get your hoses rebuilt.
I'm on the other coast and had these guys in Bear, Delaware rebuild mine and then customized mine last fall to work with Sanden conversion and the Tru-Trac serpentine system on my NYB.
www.benzhydraulics.com
I'm sure you have a hydraulic shop somewhere in California to get your hoses rebuilt.
I'm on the other coast and had these guys in Bear, Delaware rebuild mine and then customized mine last fall to work with Sanden conversion and the Tru-Trac serpentine system on my NYB.
www.benzhydraulics.com
Presumably you're referring to "new Freon" as R-134a? Rather than the yf-1234a which came later in OEM applications, which is VERY expensive??
It has been observed that the barrier-style hose for R-134a us stuffer than the OEM hoses, which means it can't make the small-radius bends as well, so plan the routing BEFORE you start matching, inch for inch, the new hose by the old hose pattern.
Just some thoughts,
CBODY67
It has been observed that the barrier-style hose for R-134a us stuffer than the OEM hoses, which means it can't make the small-radius bends as well, so plan the routing BEFORE you start matching, inch for inch, the new hose by the old hose pattern.
Just some thoughts,
CBODY67
Wow!! Seems like a LOT of stuff... perhaps it would be easier to just scrap the original stuff and get something modern... I was really hoping for a/c this summer but the budget and the time are kinda limited.... i suppose i could start by seeing if it even holds vacuum....
Orange county is driving distance to Mexico, they still have R-12 available there. You would need a speaker fluent in Spanish to communicate what you need. He/She should also know a safe area so you do not get any fingers mailed home.
Dave
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Lol!! As it happened...the guy I bought my wagon from lives near Mexicali and he agreed to drive it over there for a seat redo and headliner... he even left it overnight and went back the next day to pick it up.. he was gonna get the a.c. charged but decided he'd take it to the carwash and then didn't have enough time for the ac!!... I would much rather have ac than a carwash...uuugh...what could I tell the guy?!! A trip to TJ means a long long wait to get back across....
If I decide to do it, i will check as much as possible that it will work
65sporty
Old Man with a Hat
If you can get it charged with R-12, great. The method Dave outlined is the ultimate for long term R-134A usage. I have converted many systems by doing limited work to the system, evacuate the R-12 if system has any left in it, replace the receiver/drier, the h-block, add pag oil, pull a vacuum and recharge. They claim the years of R-12 usage will coat the inside of the hoses and help the R-134A from leaking.
70bigblockdodge
Old Man with a Hat
Flush, green O rings, new correct oil, and a new dryer.
Don't believe what people say about the hoses because after 3-4 years I'm still waiting for the 134 to leak out so I can fix a back Schrader valve on the compressor, actually I have decided to replace the RV 2 also.
Honestly doing it right, change the hoses. If you where to use a NOS hose I think it would leak like everyone says because it has never had years of oil running through it becoming the barrier.
Don't believe what people say about the hoses because after 3-4 years I'm still waiting for the 134 to leak out so I can fix a back Schrader valve on the compressor, actually I have decided to replace the RV 2 also.
Honestly doing it right, change the hoses. If you where to use a NOS hose I think it would leak like everyone says because it has never had years of oil running through it becoming the barrier.
To me, with an older systemm that's "intact", it might be good to first "test run" it with some "drop-in" R-12 replacement (from many auto supplies) first. If that works, then you'll have a better idea of what might really need replacing.
Of course, the receiver/drier will need to be replaced due to age, as the dessicant in it (which removed and holds any moisture in the system) could be "used up". Typically, replacement versions are shorter/smaller than the OEM items, but possibly some with a larger capacity could be found somewhere?
There have been many things which were first advocated in R-12 to R-134a conversions which were found to be not as originally suspected. The "seasoned hose" orientation came from thost things, I suspect. If the inner hose surface is seasoned, so will the related sealing O-rings, too, I suspect. The last word I saw claimed that if the hoses successfully held R-12, for years, then they'd probably hold well with R-134a, due to the internal surface "sealing".
The other was the amount of gas charge, independent from a manual readjustment of any internal regulating items (POA, EPR, Hot Gas Bypass, etc.) by adjusting the hidden adjustment mechanism by about 3/4 turn CCW to achieve an evaporator pressure of 26.5" Hg from the R-12 29" Hg. I found that trick in the old www.ackits.com website (moderated/run by people in the automotive a/c business), although some in here have mentioned a R-134a expansion valve. Either way, the system would need to be evacuated to do these things. Whatever works.
ONE minor/major point, though, is that if R-12 is put into a R-134a Freon recycling machine, it will contaminate that machine, such that additional functions would be needed to de-contaminate the machine for further R-134a use. The recycling machines evacuate the system, clean the gas, put new oil into the mixture, then re-charge. So putting R-12 through that R-134a-rated machine would require a it be cleaned prior to further R-134a use. I suspect that any old machines used for R-12 have gone somewhere else by now.
R-134a will take about 20% less gas than the R-12 spec. The R-12 capacity spec is usually on a tag on the existing compressor or in the factory service literature. For some, this is a starting point, though, adding gas slowly until the best/lowest vent temp is achieved. R-134a seems to be more sensitive to cooling performance decreases due to "too much gas in the system".
Just some thoughts,
CBODY67
Of course, the receiver/drier will need to be replaced due to age, as the dessicant in it (which removed and holds any moisture in the system) could be "used up". Typically, replacement versions are shorter/smaller than the OEM items, but possibly some with a larger capacity could be found somewhere?
There have been many things which were first advocated in R-12 to R-134a conversions which were found to be not as originally suspected. The "seasoned hose" orientation came from thost things, I suspect. If the inner hose surface is seasoned, so will the related sealing O-rings, too, I suspect. The last word I saw claimed that if the hoses successfully held R-12, for years, then they'd probably hold well with R-134a, due to the internal surface "sealing".
The other was the amount of gas charge, independent from a manual readjustment of any internal regulating items (POA, EPR, Hot Gas Bypass, etc.) by adjusting the hidden adjustment mechanism by about 3/4 turn CCW to achieve an evaporator pressure of 26.5" Hg from the R-12 29" Hg. I found that trick in the old www.ackits.com website (moderated/run by people in the automotive a/c business), although some in here have mentioned a R-134a expansion valve. Either way, the system would need to be evacuated to do these things. Whatever works.
ONE minor/major point, though, is that if R-12 is put into a R-134a Freon recycling machine, it will contaminate that machine, such that additional functions would be needed to de-contaminate the machine for further R-134a use. The recycling machines evacuate the system, clean the gas, put new oil into the mixture, then re-charge. So putting R-12 through that R-134a-rated machine would require a it be cleaned prior to further R-134a use. I suspect that any old machines used for R-12 have gone somewhere else by now.
R-134a will take about 20% less gas than the R-12 spec. The R-12 capacity spec is usually on a tag on the existing compressor or in the factory service literature. For some, this is a starting point, though, adding gas slowly until the best/lowest vent temp is achieved. R-134a seems to be more sensitive to cooling performance decreases due to "too much gas in the system".
Just some thoughts,
CBODY67
The reason that the crimped fittings on the R-134a hoses are different is that they don't pierce the inner surface of the hose via barbs. If the older-style barb'd R-12 fittings are used with the barrier hose, the inner barrier will be similarly pierced and negate the barrier's integrity, resulting in the leaks the barrier hose is supposed to stop. So, new hoses with new R-134s fittings, if new hoses are made up for the system. Just a point of clarification.
CBODY67
70bigblockdodge
Old Man with a Hat
About 20% less weight because the molecules are smaller in 134 than the giant R12 molecules. The volume will actually be more if compared side by side. This makes the 134 run at a higher pressure when the system is running.
Just to clarify.
From what my associate that was in the a/c aftermarket when the R-134a OEM use was being prototyped, the "people" originally told them it would take 20% more gas than the R-12 did, so that was what the earliest testing was done with. With poor cooling resulting. When somebody decreased the charge level to 20% less than R-12, then cooling performance returned. Which also tended to parallel what was later in the literature of converting to R-134a from R-12.
A full oil flush was also in the mix, in these conversions, as the R-12 oil would settle-out in the lowest sections of the system, which would decrease cooling capacity, too.
Back then, there were three types of a/c oil, depending upon the country of origin of the vehicle's system. As I suspected, now there are "universal" oils, even synthetic-based oils, which "go everywhere".
A/c condenser capacity/size is important, as is air flow through said condenser at low vehicle speeds, which is one reason the R-134a OEM condensers are larger in size than the prior R-12 items. Dedicated air flow might need an aux electric fan in some applications, for good measure.
In those earlier conversations we had, back in the '80s, he stated that the Chrysler RV-2, Ford Tecumseh, GM A-6, and other "big" compressors had enough "beef" to handle the higher R-134a pressures. The Sandens were just hitting the market at that time. One of their((OEM compressor) attributes could have been that then were all about 10cu in displacement compressors, compared to the typically 8cu in "smaller" compressors? GM upsized their R-4 compressors to 9.5cu in later on. Later comments in here speak of RV-2 failures, once converted, which makes me wonder if they were OEM production or reman units? Be that as it may.
In '80, Chrysler used to a Denso C-191 axial compressor, mounted in the normal RV-2 location, which necessitated a different engine thermostat location on the LA engines. It did great in my '80 Newport.
On R-134a systems, it's been noted that a "mass flow" condenser, rather than the earlier "serpentine flow" R-12 style condenser works best, but no real performance comparisons, that I've seen yet.
Just some thoughts,
CBODY67
A full oil flush was also in the mix, in these conversions, as the R-12 oil would settle-out in the lowest sections of the system, which would decrease cooling capacity, too.
Back then, there were three types of a/c oil, depending upon the country of origin of the vehicle's system. As I suspected, now there are "universal" oils, even synthetic-based oils, which "go everywhere".
A/c condenser capacity/size is important, as is air flow through said condenser at low vehicle speeds, which is one reason the R-134a OEM condensers are larger in size than the prior R-12 items. Dedicated air flow might need an aux electric fan in some applications, for good measure.
In those earlier conversations we had, back in the '80s, he stated that the Chrysler RV-2, Ford Tecumseh, GM A-6, and other "big" compressors had enough "beef" to handle the higher R-134a pressures. The Sandens were just hitting the market at that time. One of their((OEM compressor) attributes could have been that then were all about 10cu in displacement compressors, compared to the typically 8cu in "smaller" compressors? GM upsized their R-4 compressors to 9.5cu in later on. Later comments in here speak of RV-2 failures, once converted, which makes me wonder if they were OEM production or reman units? Be that as it may.
In '80, Chrysler used to a Denso C-191 axial compressor, mounted in the normal RV-2 location, which necessitated a different engine thermostat location on the LA engines. It did great in my '80 Newport.
On R-134a systems, it's been noted that a "mass flow" condenser, rather than the earlier "serpentine flow" R-12 style condenser works best, but no real performance comparisons, that I've seen yet.
Just some thoughts,
CBODY67
65sporty
Old Man with a Hat
When we first started doing retrofits we were told the 80% of charge rule, but as time went on they say you can use up to 100% charge level.
I think some of the confusion in that regard was because some of the converted systems probably had congealed oil still in them and could not take a full charge of either refrigerant. A properly purged and clean system should be able to use the same amount of R-134a as the system took with R-12. With R-134a the only notable difference is that as a gas, R-134a has a greater volume so it either needs more compression or a larger surface area on the condenser to bring it back to a liquid.
Dave
Some of the newer systems, in R-134a and the yf-1234a gas generally have charge levels in the 1-2lb area. Less than the old 3.5lb R-12 systems. Yet with physically larger condensers. And those "little" compressors that are on engines capable of 7000rpm, spinning faster than any former-design a/c compressor would tolerate.
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