jesus5052003
New Member
How do I read on this rear air conditioner in my 1968 plymouth sports suburban station wagon c-body 383 4bbl and how easy is it to convert or should I look for someone that adds R-12 to recharge
Air conditioner
- Thread starter jesus5052003
- Start date
R-12 dual evaporator units will usually fail if you convert them to R-134a. It is really difficult to get all of the mineral type oil out of a dual unit R-12 system prior to converting to R-134a. Any oil left in the system will turn into a jelly like snot that will not circulate and the system will likely die of oil starvation. Even with the old oil removed, R-134a is a less dense refrigerant that does not circulate oil very well, especially on dual unit systems. Ideally, you should find a shop to evacuate the system, replace the filter dryer. check for leaks, recharge the system with fresh oil and recharge it with R-12. There are also some R-12 replacement gasses available that will work better in these old systems than R-134a. R-134a is in the process of being phased out anyway. R-12 replacements are a mostly Propane/Butane blend, so there is a potential fire hazard if the gas were to happen to leak out around an electrical arc or an open flame.
Dave
Dave
Decipher the remains of the tag on the a/c compressor as to how many pounds of R-12 the full system takes. Nothing on the vehicle data plate for this.
R-12 MIGHT still be around, legally, in the USA. Seems like it ultimately takes about 20% R-134a gas to replace R-12? The full system will need to be flushed of R-12 AND the oil in the compressor changed, too. A new receiver-drier will be needed also.
Used to be that the full system would need to be evacuated by an F-12 recycling machine. The gas cleaned and new oil added. Plus the balance of what it took to get to a full charge of R-12. That particular machine was NOT universal, but unique to R-12 and other gases would contaminate it. At this point in time, finding a shop with a functioning R-12 machine might be a trick. Putting R-12 into a R-134a machine would contaminate the R-134a machine and necessitate a new 30lb cylinder or R-134a.
There are some "drop-in replacement" gas products for R-12.
Tell the shop, up front, what you have and would like to get accomplished.
Just some thoughts,
CBODY67
R-12 MIGHT still be around, legally, in the USA. Seems like it ultimately takes about 20% R-134a gas to replace R-12? The full system will need to be flushed of R-12 AND the oil in the compressor changed, too. A new receiver-drier will be needed also.
Used to be that the full system would need to be evacuated by an F-12 recycling machine. The gas cleaned and new oil added. Plus the balance of what it took to get to a full charge of R-12. That particular machine was NOT universal, but unique to R-12 and other gases would contaminate it. At this point in time, finding a shop with a functioning R-12 machine might be a trick. Putting R-12 into a R-134a machine would contaminate the R-134a machine and necessitate a new 30lb cylinder or R-134a.
There are some "drop-in replacement" gas products for R-12.
Tell the shop, up front, what you have and would like to get accomplished.
Just some thoughts,
CBODY67
LocuMob
Fluid Technician with a hat
Not claiming you're wrong, but I had a '92 Daytona I emptied the old refrigerant, and added the 134 to the system with no other change. It worked great for the three years I had the car. Nice cold air with no dropoff in performance. At the time, it was common to change a couple of smaller parts in the system and it functioned as normal. I just wasn't putting any money into that particular car, and all things worked fine for me.
Just Carbs
Well-Known Member
They generally don't have much in them when they arrive at my house after years of hibernation. Maybe 10 psi at most. Just enough to not be worried that they have been sitting at atmosphere for years.
I've been sucking the system down, emptying the compressor of oil, flushing everything else out, adding ester oil and charging the system with propane/butane.
A reduced amount of propane/butane has been needed. In other words, it takes much less to get VERY cold air with the propane/butane.
Of course, you should NOT use straight propane like I do when testing for leaks and performance and then change it out for clean propane/butane refrigerant if it all works as desired.
I've been sucking the system down, emptying the compressor of oil, flushing everything else out, adding ester oil and charging the system with propane/butane.
A reduced amount of propane/butane has been needed. In other words, it takes much less to get VERY cold air with the propane/butane.
Of course, you should NOT use straight propane like I do when testing for leaks and performance and then change it out for clean propane/butane refrigerant if it all works as desired.
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The reason your Datona "lived" is that it had a rotary vane style compressor rather that than a piston type. Makes a big difference because the rotary compressor are a lot more forgiving.
Dave
My 66 wagon with Dual AC was converted to R134a freon in the late 1990s - and still lives to tell the tale. It still cools like a freezer in there, both front and rear units. It stayed R134a for at least 20 years. I actually don't use R134A any more, I use the various Butane-based freons because it's cheaper. I guess the original evacuation was complete and no original oil remained when the system was converted. Any subsequent flushing done was done at multiple points to ensure completeness.
Regardless - there are several steps required before just recharging:
Dual AC systems such as that have their charge weights on a tag on the compressor - there is no information for that on the fender tag you posted. Typically, the dual systems in our C bodies used roughly 4 lbs of R12, but that's really not required information - yet.
First, the system has to be evacuated and see if it holds a vacuum. If it doesn't, there's a leak which needs repairing. This should be done by an AC shop - they can fill the system with an appropriate gas with a dye in it that shows leaks with UV light.
Once the leaks are repaired and the system holds vacuum (AND the compressor is able to do its job, and the pressure valves function), then you can charge the system.
Most charge weights are generic - meaning one size sort of fits all - but the best way to charge the system is to put in about 50% of a charge and start watching the temperatures at the vents. Gradually add a bit more refrigerant, and as the temps decend, watch for when they bottom out and start to rise. Take a bit of refrigerant out and that's where your system will operate the best.
Doesn't really matter what refigerant you choose to use - have it truly cleaned of every bit of old oils first by flushing at each of the major unions - replace the O rings as you go with green ones, use the proper oil that goes with the new refrigerant, and go slowly.
I have found that for R134a, about 60 - 80% of the original charge weight for R12 is about where you'll be. Butane types are maybe a tad less than that.
You do NOT need to replace all your original rubber lines if they're not leaking - that's a money grab - old barrier hoses are seasoned and will not allow new refrigerants to seep through. NEW hoses MUST be compatible with modern refrigerants, or they will leak through the material. All my original hoses are fine, no leaks or seepage.
The same with the O rings at unions - no reason to change them if they're not leaking, UNLESS you've opened the system at that point for flushing - then change the O ring to a new green one.
AC systems are actually quite simple - lots of parts, but they basically fall into these categories, and so can be gone through methodically:
Compressor
Lines
Condenser
Evaporator
Pressure regulator valves
All of these can get gummed up from poor prep and incomplete flushing when switching to new oils and refrigerants, and can stop working and require cleaning or replacement. Almost every single part is available new except for hard lines which are rarely requiring replacement, so if in doubt, replace it, or in the case of the compressor, while it's a pain, it can be rebuilt. I've gotten lucky with my compressors - again, if the prep work is done when recharging (proper flushing etc.), they're very rugged units.
Regardless - there are several steps required before just recharging:
Dual AC systems such as that have their charge weights on a tag on the compressor - there is no information for that on the fender tag you posted. Typically, the dual systems in our C bodies used roughly 4 lbs of R12, but that's really not required information - yet.
First, the system has to be evacuated and see if it holds a vacuum. If it doesn't, there's a leak which needs repairing. This should be done by an AC shop - they can fill the system with an appropriate gas with a dye in it that shows leaks with UV light.
Once the leaks are repaired and the system holds vacuum (AND the compressor is able to do its job, and the pressure valves function), then you can charge the system.
Most charge weights are generic - meaning one size sort of fits all - but the best way to charge the system is to put in about 50% of a charge and start watching the temperatures at the vents. Gradually add a bit more refrigerant, and as the temps decend, watch for when they bottom out and start to rise. Take a bit of refrigerant out and that's where your system will operate the best.
Doesn't really matter what refigerant you choose to use - have it truly cleaned of every bit of old oils first by flushing at each of the major unions - replace the O rings as you go with green ones, use the proper oil that goes with the new refrigerant, and go slowly.
I have found that for R134a, about 60 - 80% of the original charge weight for R12 is about where you'll be. Butane types are maybe a tad less than that.
You do NOT need to replace all your original rubber lines if they're not leaking - that's a money grab - old barrier hoses are seasoned and will not allow new refrigerants to seep through. NEW hoses MUST be compatible with modern refrigerants, or they will leak through the material. All my original hoses are fine, no leaks or seepage.
The same with the O rings at unions - no reason to change them if they're not leaking, UNLESS you've opened the system at that point for flushing - then change the O ring to a new green one.
AC systems are actually quite simple - lots of parts, but they basically fall into these categories, and so can be gone through methodically:
Compressor
Lines
Condenser
Evaporator
Pressure regulator valves
All of these can get gummed up from poor prep and incomplete flushing when switching to new oils and refrigerants, and can stop working and require cleaning or replacement. Almost every single part is available new except for hard lines which are rarely requiring replacement, so if in doubt, replace it, or in the case of the compressor, while it's a pain, it can be rebuilt. I've gotten lucky with my compressors - again, if the prep work is done when recharging (proper flushing etc.), they're very rugged units.
3175375
Senior Member
Air conditioning systems are relatively simple. As you describe, there are a few components. Leaking makes up over 90% of the issues.
Rubatoguy
Member
From what I have heard, to do a correct conversion to R134a, you have to change out all the A/C hoses to the new barrier type. R134a is a smaller molecule than R12 and will escape out of the old R12 hoses. So if you convert and do not change over the hoses, you will be continually adding R134a as it will leak out of the R12 hoses. Given the increasing scarcity of R12 it is a good idea to replace the factory hoses with R134 barrier hoses to help prevent leaks. I'm told any good A/C shop can make up custom hoses. However this does make things a more expensive proposition. Here is an article with good info about R12 and R134: Air-conditioning dos and don’ts: Refrigerants and the law - Hagerty Media
This is a myth, perpetuated when the conversions started, to make people in the AC business more money. It is simply NOT true, and, sadly this misinformation keeps getting sent around.
Old, seasoned and in good condition barrier hoses do NOT allow R124A seep through. New ones will unless they're R134A rated.
If you just upgraded to the newer barrier hoses, the older "barb" OEM connectors would pierce the barrier and leaks would happen. This is the reason for the newer "bead-lock" connectors and distinctive clamping pattern on the hose ends. No piercing of the inner barrier, that way.
A LOT has been learned since R-134a was first used. A main thing is that the R-12 oil seasons (and seals) the innards of the hoses and related connections. If they are not leaking with R-12, they will not typically leak with R-134a. So rather than a "replace" orientation to hoses, it becomes a "try it and see with R-134a gas". In many cases, the old hoses are aged and need replacement anyway, so prepare to use all new hoses, connectors, and o-rings in the system. Plus a new receiver-drier too.
On many C-bodies, the metal lines which run along the rh upper fender do not need to be replaced, unless they are leaking and can't be brazed back together.
Search for a thread by "TxDon" on converting his '66 Monaco wagon to R-134a. He managed to source everything to do the deal for pretty good prices. Some assy required, though.
As things have evolved, "Better Living Through Chemistry" has happened as rather than three oils, there are fewer oils which can have universal compatibility with R-12, R-134a, and others.
R-134a is related to the newer gas now used in current OEM systems. That gas is very expensive, which definitely requires a recycling machine! As I have noticed an online mechanic has used R-52 as a drop-in replacement. R-134a might be on the way out, but it might still be a good while before that happens.
Enjoy!
CBODY67
A LOT has been learned since R-134a was first used. A main thing is that the R-12 oil seasons (and seals) the innards of the hoses and related connections. If they are not leaking with R-12, they will not typically leak with R-134a. So rather than a "replace" orientation to hoses, it becomes a "try it and see with R-134a gas". In many cases, the old hoses are aged and need replacement anyway, so prepare to use all new hoses, connectors, and o-rings in the system. Plus a new receiver-drier too.
On many C-bodies, the metal lines which run along the rh upper fender do not need to be replaced, unless they are leaking and can't be brazed back together.
Search for a thread by "TxDon" on converting his '66 Monaco wagon to R-134a. He managed to source everything to do the deal for pretty good prices. Some assy required, though.
As things have evolved, "Better Living Through Chemistry" has happened as rather than three oils, there are fewer oils which can have universal compatibility with R-12, R-134a, and others.
R-134a is related to the newer gas now used in current OEM systems. That gas is very expensive, which definitely requires a recycling machine! As I have noticed an online mechanic has used R-52 as a drop-in replacement. R-134a might be on the way out, but it might still be a good while before that happens.
Enjoy!
CBODY67
marty koirtyohann
Well-Known Member
what kind of ac compressor r u going to use with the 134a? i how not the RV2? WITH OUT A POA 134 Valve( they dont mak one now !) IT WILL NOT work RIGHT u can switch it over tp a rotary style but its a differant belt set up . i know i fought that wih my 72 440 new yorker
Chrysler did not use a POA valve, but an inline Evaporator Pressure Regulator valve that is internal to the metal line on the compresor fitting. It IS adjustable, turn the adjustment about 3/4 turn CCW to use R-134a. I found out about that about 20 years ago, from the old www.ackits.com website. Run by automotive a/c people in AZ. With that adjustment (which some in here have claimed is not needed due to the expansion valve in the system), pressure relationships become more like the R-12 pressure relationships, they said. No mention of the RV-2 not being able to handle the pressures in that forum.
In the 1990s, I had a friend (former Chrysler parts person) who went to work for a noted automotive a/c parts company. When they were doing the initial research on OEM R-134a. He said the RV-2, Tecumseh (Ford), and GM A-6 compressors were all strong enough to handle the higher pressures with no issues, back then. I trust his information. Perhaps newer replacement RV-2s are different?
After the minor EPR adjustment, everybody in that ackits.com forum said they were getting approx 40 degree F vent temperatures. The later-developing possibility is that the diaphrams in the EPR valves might be getting old and might fracture if an adjustment is attempted? Which means a Chrysler A-body adaptation of a pressure cycling switch, possibly on the receiver-drier where the current low pressure switch is located, might be an alternative. A-bodies used the cycling switch with RV-2s as B and C-body cars used the EPR instead.
There are several threads in here on Sanden conversions. Less weight and drag on the motor.
Later recommendations are to replace the OEM serpentine condenser with a "mass flow" condenser as the newer OEM R-134a systems use. This would be a universal-type item in the aftermarket and might require some different bracketry and plumbing to secure it to the vehicle.
Take care,
CBODY67
In the 1990s, I had a friend (former Chrysler parts person) who went to work for a noted automotive a/c parts company. When they were doing the initial research on OEM R-134a. He said the RV-2, Tecumseh (Ford), and GM A-6 compressors were all strong enough to handle the higher pressures with no issues, back then. I trust his information. Perhaps newer replacement RV-2s are different?
After the minor EPR adjustment, everybody in that ackits.com forum said they were getting approx 40 degree F vent temperatures. The later-developing possibility is that the diaphrams in the EPR valves might be getting old and might fracture if an adjustment is attempted? Which means a Chrysler A-body adaptation of a pressure cycling switch, possibly on the receiver-drier where the current low pressure switch is located, might be an alternative. A-bodies used the cycling switch with RV-2s as B and C-body cars used the EPR instead.
There are several threads in here on Sanden conversions. Less weight and drag on the motor.
Later recommendations are to replace the OEM serpentine condenser with a "mass flow" condenser as the newer OEM R-134a systems use. This would be a universal-type item in the aftermarket and might require some different bracketry and plumbing to secure it to the vehicle.
Take care,
CBODY67
marty koirtyohann
Well-Known Member
WELL IDF U SAY SO MY COUSIN WAS A CERTIFIDE AUTO AC TECH HE HAS THE PERMOT TO USE R 12 ITS STILL THE BEST REFRIGERANT . NOW DO U HAVR A 4 OR 5 BO;T AC COMPRESSOTR TE 4 BO;T WAS USED ON SMALL BLOCKS & the 5 BOLT WAS USED O BG BLOCKS . RICH TRYED TO DO WHAT U SAID & THE EAC JUSTWOULDNT WORK WHEN DRIVING DOWN THE ROAD / I HAD 35 DEGREE AIR COMING OUT MY MAOIN DUCTS THE VALVE IM TAKNG ABOUT WEBNT IN THE BACK OF THE RV2 COMPRESSOR TILL THE PARTS STORE REBUILR 4 BOLT DIDED T BLW HE FROUNT SEAL THEN MY CAR FT WECKED SO I NO LONGER HAD A C BODY IM BACK TO A TRUCK AGAIN ^ ITS COMPRESSOR IS A DIFFEANT STYLE I TRUST HIS SKILL & knolage AFTER ALL HEWAS TRAINED N AC BY CHRYSLERV& gm hes IN HS MOID 60
S HES BEEN DOING IT FOR YRS & he has 4 MOPARS & so domy cousunS THEY ALL HAV THE OLD MOPARS THE ONE HAD A GY FROM A INDIPENDEANT SHOP 'BURNIUP A RV2" TRYG GTO PU 134A IN IT IT WAS FINE IN THE SHOP BUT WHEN IT WAS ONTHE ROAD IN 90-100 DEGREE OUTSIDE TEMP IT WOULDNT COOL WHILE MY R12 WAS JUST FINE . I HAVE HEARD OTHER GUYS SAY 134A WORL JUST FNE TOIL THEY RIDE IN OUR CARS
NOW IF U CAN GET IT TO BLOW COLD AIR WHILE RNNNG DOWN THE ROAD GREAT BUT WE CANT
S HES BEEN DOING IT FOR YRS & he has 4 MOPARS & so domy cousunS THEY ALL HAV THE OLD MOPARS THE ONE HAD A GY FROM A INDIPENDEANT SHOP 'BURNIUP A RV2" TRYG GTO PU 134A IN IT IT WAS FINE IN THE SHOP BUT WHEN IT WAS ONTHE ROAD IN 90-100 DEGREE OUTSIDE TEMP IT WOULDNT COOL WHILE MY R12 WAS JUST FINE . I HAVE HEARD OTHER GUYS SAY 134A WORL JUST FNE TOIL THEY RIDE IN OUR CARS
NOW IF U CAN GET IT TO BLOW COLD AIR WHILE RNNNG DOWN THE ROAD GREAT BUT WE CANT
There is plenty of R12 in the small cans out there and it is legal to possess it...even sell and ship it. I just sold my stash to a guy at great profit to me.R12 is the only way to go in your case.
3175375
Senior Member
R12 is stupendously more effective and forgiving than R-134a. Period.
R-134a takes more time and effort, measuring pressures and evaporator temperatures than R-12. Additionally, you can run the R-12 systems low (up to 20-30%) and I believe higher (although you can easily not overcharge it as you’re done when the sight glass is clear).
R-134a takes more time and effort, measuring pressures and evaporator temperatures than R-12. Additionally, you can run the R-12 systems low (up to 20-30%) and I believe higher (although you can easily not overcharge it as you’re done when the sight glass is clear).
NOT trying to trash R-12 OR elevate R-134a! NOT seeking to imply that some failures in the conversion process did not happen, either! Just reporting what I read and which made sense to me.
In the 1990s when R-12 importation was heavily criminalized and becoming very expensive (for the purchaser and also with possession taxes on the seller), we were in transition stage. The HUGE conspiracy of the chemical companies regarding why R-12 became so "bad" were rampant, but we had NO way to get around these things. Forums were full of "I used _______" and use of "modified R-12" posts. I lived through all of that. I ALSO noticed that the performance of OEM R-134a systems was pretty good. A lot of that focused on the size and airflow through the condenser.
To me, the RV-2 and Tecumseh compressors were too big, too heavy, and too power-hungry, but they were smaller than what came before them in the 1950s. Rougher-running than the smoooth GM A-6, by observation.
In our '66 Newport, it became apparent that the factory system was over-sized for what was needed. The cooling between a fully-charged system and when it would get to be "1 lb low", was minimal at best, but once it passed that level, system performance quickly diminished in the TX summer heat.
Having such stellar performance on the '66, the '72 Newport was not that good. Apparently the system was not up-sized to account for the larger interior volume. For cooling performance OR airflow requirements, so our '72 never did cool as well as the '66 Town Sedan did. Yet my '60 Monaco 4drht was in-between, with its smaller interior volume.
Just my experiences,
CBODY67
In the 1990s when R-12 importation was heavily criminalized and becoming very expensive (for the purchaser and also with possession taxes on the seller), we were in transition stage. The HUGE conspiracy of the chemical companies regarding why R-12 became so "bad" were rampant, but we had NO way to get around these things. Forums were full of "I used _______" and use of "modified R-12" posts. I lived through all of that. I ALSO noticed that the performance of OEM R-134a systems was pretty good. A lot of that focused on the size and airflow through the condenser.
To me, the RV-2 and Tecumseh compressors were too big, too heavy, and too power-hungry, but they were smaller than what came before them in the 1950s. Rougher-running than the smoooth GM A-6, by observation.
In our '66 Newport, it became apparent that the factory system was over-sized for what was needed. The cooling between a fully-charged system and when it would get to be "1 lb low", was minimal at best, but once it passed that level, system performance quickly diminished in the TX summer heat.
Having such stellar performance on the '66, the '72 Newport was not that good. Apparently the system was not up-sized to account for the larger interior volume. For cooling performance OR airflow requirements, so our '72 never did cool as well as the '66 Town Sedan did. Yet my '60 Monaco 4drht was in-between, with its smaller interior volume.
Just my experiences,
CBODY67
Having used all 3 types of refrigerant over the last 30 years (R22, R134A, and butane types), it's all about optimizing pressure and charge weight to maximize cooling performance. Regarding the valves - I have run my systems with and without the various pressure valves as well - currently running with them installed. No change in performance.
ALL my AC equipped C bodies have had excellent AC performance, driving or not.
I will post a picture of the kind of temps I get from the vents when I can find it.
ALL my AC equipped C bodies have had excellent AC performance, driving or not.
I will post a picture of the kind of temps I get from the vents when I can find it.
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