I just got the truck back on the road after some much needed cosmetic repairs to her body. Now the A/C has lost its charge. This is an original R-12 system. Should I spend the cash to re-charge with R-12 or do the conversion to the R-134 refrigerant? I did the 134 conversion to my 89 gasser and was never really content with the performance of the system after that. What are you guys running in your systems?
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A/C Opinions
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I've been doing auto A/C work for over 30 years. I've tried various conversions on our G. Caravans. 134 doesn't work well and in many conversions has destroyed compressors although that can be handled with careful conversion in most cases. It does run higher head pressures than R12 and really needs a larger condensor coil in most cases. Freeze 12 works fairly well. Autofrost works well, but is an R22 blend and it appears to destroy compressor shaft seals after a year or two. Best results all around have been with HC-12, a superrefined propane. The only objection to HC is the possibility of fire from a leak. That appears to be a non issue in the real world. For one thing you use about 1/3 the amount by weight of R-12 which means that in a typical system you're running less than 12oz. of propane. That's not enough to do much even if you could get it all the ignite at one time. For another thing, conventional refrigerants are all flammable as well and R134 has a lower flash point than HC-12. Some states ban the use of "flammable" refrigerants such as propanes, but that's sort of odd when the conventional stuff is as bad or worse. HC is cheap, blends perfectly with any lubricant, is more efficient than any other refrigerant, does not attract moisture and leaks more slowly than conventional refrigerants due to larger molecules.
Purchased three cans last year from http://hc12ausa.com/
It works wonderfully, even with the high humidity of south Georgia
It works wonderfully, even with the high humidity of south Georgia
I would not convert to 134A, it is the eventual kiss of death and a for sure down the road expense, too hard on the compressor.
Here's another alternative refrigerant,
http://es-refrigerants.com/
other info and refrigerants,
http://autorefrigerants.com/
http://store.ackits.com/
http://www.sanden.com/support/servicemanual/english/table_of_contents.html
Here's another alternative refrigerant,
http://es-refrigerants.com/
other info and refrigerants,
http://autorefrigerants.com/
http://store.ackits.com/
http://www.sanden.com/support/servicemanual/english/table_of_contents.html
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PToombs
TDR MEMBER
I did a 134 conversion on a 91 astro van. It worked flawlessly for the 3 or 4 years we kept it after I did it.
My wifes 96 Grand Cherokee, on the other hand, has it from the factory, and needs to be charged twice a year. I ran the sniffer over it, tried some sealer additive. I can't find a leak but it still goes out! #@$%!
My wifes 96 Grand Cherokee, on the other hand, has it from the factory, and needs to be charged twice a year. I ran the sniffer over it, tried some sealer additive. I can't find a leak but it still goes out! #@$%!
Can the HC12 be added to the existing R12 charge as a topping charge?
On R134A systems, they seem to work better if slightly over-charged - the following notes may help:
R 134a Charging Notes
• Charge on low pressure side only
• Charge gas only
• Hook up and use gauges.
• Charge is complete when the low pressure hose is cool about 6” out of the receiver / evaporator – towards the compressor . . . . . this is because there is still liquid in the hose but it is gas by the time it gets to the compressor.
• Keep the high pressure side as low as possible – since the unit will be running high cool – with the car at standstill – put a garden hose with running water on the condenser – should see high side pressures at 160 to 180 psi, max
• Low side pressure should be 30 to 40 psi with compressor on in max A/C position
• To overcharge by approximately 6% - may have to warm up the refrigerant can. However, make sure that the low pressure hose does not get any colder than described above.
On R134A systems, they seem to work better if slightly over-charged - the following notes may help:
R 134a Charging Notes
• Charge on low pressure side only
• Charge gas only
• Hook up and use gauges.
• Charge is complete when the low pressure hose is cool about 6” out of the receiver / evaporator – towards the compressor . . . . . this is because there is still liquid in the hose but it is gas by the time it gets to the compressor.
• Keep the high pressure side as low as possible – since the unit will be running high cool – with the car at standstill – put a garden hose with running water on the condenser – should see high side pressures at 160 to 180 psi, max
• Low side pressure should be 30 to 40 psi with compressor on in max A/C position
• To overcharge by approximately 6% - may have to warm up the refrigerant can. However, make sure that the low pressure hose does not get any colder than described above.
LOL You guys crack me up!
When **I** suggest HC12a I recieve hate mail.
The whole EXPLOSION thing comes from a service station/garage testing for a refrigerant leak with a flame tester, not knowing it has been converted from CFC12 to HC12a
It is perfectly normal to use the flame test for CFC12 , but NOT such a good idea to use the flame on a HC12a filled system. :-laf
I have had a leak and I, along with my truck truck, are still alive and well. I ruptured the condensor and lost the charge.
Oh well... ... ... that HC stuff is REAL cheap not to mention it holds 1/3rd the amount of the original CFC refrigerant. I fill with 14oz compared to 44oz
My windows frost over Oo.
When **I** suggest HC12a I recieve hate mail.
The whole EXPLOSION thing comes from a service station/garage testing for a refrigerant leak with a flame tester, not knowing it has been converted from CFC12 to HC12a
It is perfectly normal to use the flame test for CFC12 , but NOT such a good idea to use the flame on a HC12a filled system. :-laf
I have had a leak and I, along with my truck truck, are still alive and well. I ruptured the condensor and lost the charge.
Oh well... ... ... that HC stuff is REAL cheap not to mention it holds 1/3rd the amount of the original CFC refrigerant. I fill with 14oz compared to 44oz
My windows frost over Oo.
amazing the different views here. i have converted at least 10 older vehicles to 134a, with no failures. and in almost all cases, the air conditioning worked better than with the r12.
i also UNDERCHARGE the system slightly (90% of recommended) to keep the air outlet temp cooler.
134a has a slightly different pressure/temperature characteristic than r12.
as long as your vehicle cycles the compressor on low side (suction) pressure, you should not have icing issues.
if you undercharge too much, the compressor will cycle too often.
the main key is to buy the complete conversion kit that includes the oil and other additives.
just my . 02 and experience
jim
BTW i have about 1/2 of a 30 lb cylinder of R12 and some R12 14oz cans gathering dust on the shelf.
i also UNDERCHARGE the system slightly (90% of recommended) to keep the air outlet temp cooler.
134a has a slightly different pressure/temperature characteristic than r12.
as long as your vehicle cycles the compressor on low side (suction) pressure, you should not have icing issues.
if you undercharge too much, the compressor will cycle too often.
the main key is to buy the complete conversion kit that includes the oil and other additives.
just my . 02 and experience
jim
BTW i have about 1/2 of a 30 lb cylinder of R12 and some R12 14oz cans gathering dust on the shelf.
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I would strongly suggest not overcharging with 134. It runs higher head pressures that 12 to begin with and overcharging makes this worse. A correct conversion to 134 also must include a high pressure cutout switch for the compressor clutch because the system will run higher pressure than it should at idle on a hot day. And that's also a legal requirement which no one ever seems to pay attention to.
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KOG - good catch. . . . . those R134A notes are for 134A systems, not conversions from R12 to R134A . . . also those notes specifically state to use gauges while re-charging and or topping off. I should have been clearer in my posting and I hope this did not confuse anyone. 
One of the biggest issues with converting from R12 to R134A is the type of compressor oil that was originally charged into the system - R12 was tolerant of several different types of compressor oils. The only refrigerant / compressor oil that will work, long term, in the conversion from R12 to R134A is PAG - there are at least two other types of common compressor / refrigerant oils that have been used (ester based and mineral based) - and you guessed it - PAG is not compatible with the ester based or mineral based oils. If PAG was not originally charged into the system, then it will have to be flushed and charged with PAG when the R-134A is charged back into the system.
In the late 1990's I worked at the R&D and petrochemical manufacturing facility that made most of the country's PAG refrigerant compressor oil - we were looking for a way to solve some of the compatibility issues noted above. One of the methods we experimented with was HC-12 and it worked very well. . . .
We experimented with R-12 equipped vehicles - not laboratory equipment. If the vehicle originally contained R-12 and PAG oil then we replaced a couple of O-rings and charged R-134A directly into the systems after evacuating all of the original R-12 out of the system - for this type of conversion, we based charge on pressure cycling points - not weight. Higher head pressures at idle were the major concern as noted by others in previous postings. All conversions made cool air - some were much better than others. . . . . One additional note. . . . . a local truck shop here in eastern Idaho claims to have performed 200 + R-12 to R134 conversions by flushing the system, changing the o-rings and changing the oil to PAG if required - no problems noted.
Finally, regarding propane in R-12 systems. . . . . a major semi-truck repair facility in Utah (in the late 1990's time frame) was 'repairing' R-12 systems with propane from a 20 lb propane barbecue cylinder. The BBQ propane worked very well and the R-12 systems produced lots of cold air. . . . unfortunately this is not purified propane, and it contains trace amounts of air, etc. . . . . so when the truck hauling hazmat ruptured a condenser in an accident the fire was very impressive and propane in R12 systems go a very bad name
Hope this helps a bit. . . . .
One of the biggest issues with converting from R12 to R134A is the type of compressor oil that was originally charged into the system - R12 was tolerant of several different types of compressor oils. The only refrigerant / compressor oil that will work, long term, in the conversion from R12 to R134A is PAG - there are at least two other types of common compressor / refrigerant oils that have been used (ester based and mineral based) - and you guessed it - PAG is not compatible with the ester based or mineral based oils. If PAG was not originally charged into the system, then it will have to be flushed and charged with PAG when the R-134A is charged back into the system.
In the late 1990's I worked at the R&D and petrochemical manufacturing facility that made most of the country's PAG refrigerant compressor oil - we were looking for a way to solve some of the compatibility issues noted above. One of the methods we experimented with was HC-12 and it worked very well. . . .
We experimented with R-12 equipped vehicles - not laboratory equipment. If the vehicle originally contained R-12 and PAG oil then we replaced a couple of O-rings and charged R-134A directly into the systems after evacuating all of the original R-12 out of the system - for this type of conversion, we based charge on pressure cycling points - not weight. Higher head pressures at idle were the major concern as noted by others in previous postings. All conversions made cool air - some were much better than others. . . . . One additional note. . . . . a local truck shop here in eastern Idaho claims to have performed 200 + R-12 to R134 conversions by flushing the system, changing the o-rings and changing the oil to PAG if required - no problems noted.
Finally, regarding propane in R-12 systems. . . . . a major semi-truck repair facility in Utah (in the late 1990's time frame) was 'repairing' R-12 systems with propane from a 20 lb propane barbecue cylinder. The BBQ propane worked very well and the R-12 systems produced lots of cold air. . . . unfortunately this is not purified propane, and it contains trace amounts of air, etc. . . . . so when the truck hauling hazmat ruptured a condenser in an accident the fire was very impressive and propane in R12 systems go a very bad name
Hope this helps a bit. . . . .
As RWWinslow noted:
DO NOT use barbeque propane. It will cool. And its flash point is quite low. Also, LABEL your system when any conversion is done. This is not only a legal requirement, it's a practical one.
Note: It's not legal, for some obscure reason, to convert from R12 TO HC12. Legally you are required to first convert to 134 and then you are allowed to convert to HC12. I have no idea which lawyer/politician posing as someone who had a clue came up with this BS, but be aware that I didn't tell you that you could convert directly. You figured that out on your own. And that's if you live in a state which doesn't prohibit the use of HC for whatever other probably spurious reason.
DO NOT use barbeque propane. It will cool. And its flash point is quite low. Also, LABEL your system when any conversion is done. This is not only a legal requirement, it's a practical one.
Note: It's not legal, for some obscure reason, to convert from R12 TO HC12. Legally you are required to first convert to 134 and then you are allowed to convert to HC12. I have no idea which lawyer/politician posing as someone who had a clue came up with this BS, but be aware that I didn't tell you that you could convert directly. You figured that out on your own. And that's if you live in a state which doesn't prohibit the use of HC for whatever other probably spurious reason.
When I purchase the HC12a I recieve several lables.
Nobody has yet to mention the capilary tube adjustment. I went as far as removal on one of the trucks. I don't know if I would recommend this, however so far so good. I tied the wires together and removed the tube from the suction hose.
I think the idea is to have the compressor in constant operation... ... ... . ???. That is, it will not cycle when in operation at 1400 rpm/above. The capilary tube along with the charge (amount of refrigerant) will determine the operation and cycling.
I pulled the tube almost all the way out on my 92 and it got a bit colder but still cycles at 1400, I think. Last I checked. It seems to work well, so I leave it well alone.
I like the comment ; "charge till you get the proper operation and not by a set amount". That's the truth. I charged like I was told and the pressure valve blew off,venting the charge. You should be somewhere at 12/14 oz of HC12a.
They tell you in the instructions that too little of HC charge will result in too cold of air.
Too cold? I guess it could frost over the evap?
Nobody has yet to mention the capilary tube adjustment. I went as far as removal on one of the trucks. I don't know if I would recommend this, however so far so good. I tied the wires together and removed the tube from the suction hose.
I think the idea is to have the compressor in constant operation... ... ... . ???. That is, it will not cycle when in operation at 1400 rpm/above. The capilary tube along with the charge (amount of refrigerant) will determine the operation and cycling.
I pulled the tube almost all the way out on my 92 and it got a bit colder but still cycles at 1400, I think. Last I checked. It seems to work well, so I leave it well alone.
I like the comment ; "charge till you get the proper operation and not by a set amount". That's the truth. I charged like I was told and the pressure valve blew off,venting the charge. You should be somewhere at 12/14 oz of HC12a.
They tell you in the instructions that too little of HC charge will result in too cold of air.
Too cold? I guess it could frost over the evap?
As someone else reported, I had my Astro converted by a commercial AC place. They guaranteed me it would work perfectly or I did not owe them anything, so I let them convert it. Six years of constant running the AC, all is still working just fine, I think colder than the R12 did. I am down on the Mexican border so getting R12 was NOT a problem.
Believe they still make it down there and up in Canuck land. Bought some a few years back, came in DuPont cans, but had the 134 style connector on top of the can, just used my snap can outfit on them.
I would like to clarify why I would not recommend the 134A conversion in a Dodge truck with the Sanden compressor that originally used R12. The 134 requires pressures that will wear out our compressor, any reputable shop would tell you that before converting one, and hopefully offer you an alternative. Last summer I had one offer a couple options to include putting R12 back in. If you had success converting your GMC etc. , Ok I am happy for you that you got some value for your money. But I would not want to spend money on a conversion that is a known issue if your compressor is to be reused. As for the other comment of converting 10 vehicles without problems, were these all Dodge trucks with Sanden compressor? When answering questions like these I like to see replies that compare apples to apples not comparing apples to oranges so-to-speak.
Correct me if I'm wrong, but don't the 134 a Rams... 94 and up. . use the same compressor, or are the insides different?
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