Converting R12 to R134a
 

My 1987 560SEL needs some attention to the A/C.

What should be replaced to get a reliable A/C system
that runs on R134a ?

What problems have you experienced converting ?

thx

After converting over a thousand cars, we no longer do it. The most important reason is there is no reason to do it. Refrigerant is one of the cheapest parts in an AC and R12 shows no sign of going away. We have paid less and less for R12 over the last 3 years.

The best that can happen with a conversion is that you will not notice the lack of efficiency of the results and you won't realize why your compressor will be leaking in a year or two if original or 2-3 years if replaced new.

Many reasons to not do it and none to do it, convinced me.

How to unconvert
 

How big a deal is it to convert a W123 from R134 back to R12 ?

I would prefer to flush the system, reoil and recharge.

DON'T CONVERT. I was ignorant at the time when I did. I wish I hadn't converted. I'd be a lot cooler here in Texas. Nothing resembling cool coming from the vents.

I have done a few reverse converts as Steve describes with great success.

It still amazes me how much money some folks will spend to convert to a different refrigerant because it costs $10 or $15 per pound less. I went toschool in the fifties and sixties before the so called "new math." Maybe this is why I don't understand the math involved that causes someone to spend hundreds of dollars so that they can use refrigerant that costs $40 or $50 less per charge. I guess I'm just too old to have such math skills.

Have a great day,

Over the years I've talked to AC pros like the vendors of AC service equipment at SEMA. They all consistently say to stay with R-12 as long as it is available. This above is primarily due to the loss of cooling capacity that is inherent when systems originally designed for R-12 are converted to R-134a.

Also, there are huge stockpiles of R-12, but fewer older cars that use it due to conversions and just lack of willingness on the part of owners to spend money on any AC service for older cars.

As a result, they predict that the price of R-12 will continue to decline.

Duke

Being a GM tech for 16 years I would retrofit to 134A. I have done a lot of retrofits with now problems at all and I don't where most people are located but here in PA R12 is very expensive and hard to get. It usually pays to retrofit then to add the R12 again especialy if you have repeat freon leaks. The cars that I have done including my own(92 Elderado) had the same vent temp or colder. If done properly it works very well but some people just evacuate the R12 and add 134 which is not a good idea. Here's what I do. I evacuate the R12 twice, on most cars I replace the acumulator where the desicant bag is located, change the fittings, connect the ACR2000 134 machine and flush the system. The ACR2000 actualy flushes the system and all of the oil with 134 for about 15 minutes, on most car you have to remove the orifice and/or expansion valve when flushing. It's a good idea to replace them anyway if contaminated with metal or desicant. Then I evacuate and add the correct amount of PAG oil that is recommended for R12 and 134 compressors. Then I charge system. You have to add a little more 134 then the recommended amount of R12. I think it's like 10% more but I just add it until it gets as cold as possible. Well worth it!

In Australia, I am under the impression that R12 is not available at all (illegal?). I have had my 1987 300SE converted two years ago, together with a rebuilt nippondeso compressor. The compressor leaked from day one after the conversion. Six months later, I had the compressor rebuilt again (under warranty). Now, 18 months later and all is fine and still cooling well.
My question to Steve is that while I understand the original compressor would have been designed for R12, surely the rebuilt one will be rebuilt with components for 132 refrigerant and therefore last as long as the original compressor?

I have great respect for Larry and Steve but I must add my free comments (not worth $.02). Here in NC the going price to completely evac and charge a 2 lb system with R-12 is about $200 last time I checked. To do the same with R-134 is about $100. To convert a system with no problems will run more depending on what work needs to be done, for instance how old is the dryer, what switches the system has that need to be changed, etc.
On my personal 84 500SEL, when I needed to change the old A-6 compressor, I converted to R-134. I had problems at first trying to get the correct charge in the system because I had problems finding out exactly how much R-12 freon it was should have. I know, look at the sticker on the rad support, but my car didn't have one. Mitchell says one thing, Alldata says something else, 2 indies in the area told me different amounts which didn't match what Mitchell or Alldata said. And guess what, the dealer came up with a completely different amount.
From this, I believe that the problem with most conversions is not having the correct amount of R-134 in the system. I've explained my proceedure before but in short I add about 16oz of freon. Set RPM to about 1500. Check center duct temp. Let the temp stabalize for a couple of min. Add 2 oz of freon. Check temp again. Keep doing this until the temp doesn't drop anymore. My system has worked great for about 3 years (I think). A friends 87 420 was done the same except nothing was changed except the compressor (used). Converted and charged the same way and he has had no problems and works great.
Now the only thing I can say is logistics and proceedurs come in to play here.
By the way, on a trip to sunny FL. this summer, my car A/C worked fine keeping the inside temp around 72deg. This is in a dark blue car with NO window tent and 4 people.
By the way, a local shop found a great buy on some R-12 this summer and when it was check, he found it contained propane. You should have seen a demo he gave me using some of this R-12 and a match. He was so upset he turned it over to the EPA who told him this is not the first case they have seen.

Sorry for the long post.

The problem with compressors leaking probably has nothing to do with the components. The problem probably is related to the higher pressures the system runs at and the change in lubricating properties of the new refrigerant oil package.

My shop has easily done over a thousand conversions, I don't think we did any this summer but we might have. If you come in dead set on converting who are we to argue?

We have made a lot of cars work just fine....for the moment, converting to 134. After a lot of experience we know the real results and as I said above, there is no reason to convert and there is many reasons not to.

As to the original question: "What should be replaced to get a reliable A/C system that runs on R134a ?" The answer is: the car!

pmckechnie,

The $100 difference between R12 and R134 is excessive. R12 can be had for about $15 a can now. Typical R134 is about $5 a can. Three cans, means $20 difference.

I have read LOTS of information about conversion and I don't think I have read or talked to ANYONE with a larger experience base than Steve Brotherton. He is highly educated, highly experienced and highly analytical. I have yet to find anyone with a large enough experience base that can refute any of his findings on this subject.

The only other person with a large experience base that differs posted in this very thread. He, however, has worked strictly with GM cars AND not in a hot climate. Steve is in a VERY hot climate just as I am, and works mostly with European cars which often have marginal a/c systems. The GM cars that I have converted have indeed held up well, but they suffer a little in performance in the 108 degree heat.

The cars originally built with R12 system are hitting the salvage yards in record numbers every day which is heavily decreasing the demand for R12. I am one of the nuts that continues to drive older cars so I watch the R12 price indicators. It is going down.

I am down to about 6 pounds of R12 in my posession, but if something happened to my R12 systems and I ran out, I would spend a few hundred dollars for a 30 pound can and most likely have enough to last the rest of my life. Would it be economical for me to convert my old cars to 134 to save that few hundred dollars in the long run? I don't think so.

That is not even considering the risk of the added pressure trashing a compressor that would then require disconnecting EVERYTHING in the system to THOROUGHLY flush out the debris before the new compressor.

For me saving $300 for a cannister of R12, that risk is just not worth it. And I am about the biggest tightwad, cheapskate you'll ever know. I won't spend $300 unless I have to.

BTW, I have been watching R12 prices this summer and I fully expect that this winter will be a time when you can buy R12 for the lowest cost in SEVERAL years.

Have a great day,

I had both my cars (1984 300SD and a 1984 380SL) converted to 134a by a professional (name withheld). The tech convinced me to do it when I had to replace the compressors. I can now tell you that it was one of the biggest mistakes I've ever made. The SL isn't bad, but my navy blue SD hits 80 degrees in the car on a hot day in traffic. :eek: The next service that I have done I'm going to have them evacuate the system and recharge it with R12. All I can say is pay the extra bucks and recharge with R12. :mad:

Your system was designed to use R12 even though you can convert to R134a
it will not be as good or perform as well.
Your choice

You're all lucky you don't live in Canada!
 

I'm green with envy...here, people have been jailed for illegally importing R12! :eek: We have a peculiar government mentality here, and an even stupider segment of the populace that backs them up. In complete disregard of the fact that every air conditioner and refrigerator is full of R12, the stuff has been illegal to sell or import for years now, but it's OK to keep it in your car's system - just next to impossible to buy, so we have to convert if it leaks.

I once checked on the price in nearby Maine for an R12 recharge, and it would've been about the same as converting to the then popular 134A, so I didn't.

My local shop replaced mine with something called 'AC-Freon R414B (59)' this past spring. I'm scared to know what the hell that is, but it's worked well for me over the summer, which of course, wouldn't have been as warm as even New England was. I don't know why 134A is no longer in vogue here.

R414B is a blend of R-22, R-124 and R-142b with hydrocarbon R-600a (isobutane) added to improve mineral oil miscibility. Not my first (or second) choice for automotive refrigerant.

I've converted quite a few vehicles (a couple GM's and the remainder MB's) from 134 back to 12 with a great deal of success. I have just recently converted a '82 300SD to 134 (it was a wreck rebuild) and went with a parallel flow condenser during the rebuild. It seems to be working fine for right now and the pressures were not really that much higher than 12. I would not convert one without going with the parallel flow condenser though.

Steve or Larry
I would love to find a 30 lb cyl of GOOD r12 in our area. The cheapest I could find today was $550. I can't justify that much to gain a few deg if my system works fine now. Remember, I said logistics plays into the equation. I totally agree that you need all the cooling you can get. In NC I have not been disappointed with my system even on the hottest days in traffic. I realize I can't win this argument so I will shut up.
Have a great day.

For Canadians that might be reading this, R12 is NOT available any longer, and if your AC system requires service, it must be converted to R134A.

I converted one of my cars, a 1993 Nissan Quest, from R12 to R134a, and it was a disaster.

On hot days the car would cool just o.k. when driving on the highway, but it was less than adequate at an idle or in city traffic.

It was so unsatisfactory that I had it converted back to R12.

Just my $0.02..... (and another $1.98 will buy you a small cup of coffee at Starbucks). :rolleyes:

pmckechnie,

By taking an online 609, open book test for $15, you can purchase R12 on ebay and you don't have to buy a 30 pound container. You can buy a few cans here or there. 30 pound containers are going as low as $300.

Actually, even to buy it locally you have to have a 609 cert to do it legally.

Have a great day,

At my office I have some old issues of Mercedes Benz Club of America STAR magazine, I was just reading a few hours ago an article about this very subject in the September/ October 2002 issue. A worthwhile issue to buy if your going to convert. or just to learn about the conversion, or stay with R12

Mines OK
 

Well I'm one of those guys that lives in Canada, Ontario specifically. My 89 420 SEL was converted to 134a, with a new drier, and seems to work fine. Car is black so it gets hot on the outside, but it is cool on the inside. But then again, we had a cool summer.

Larry,
I have 609 cert and have had it since it was introduced. I have been working on auto a/c for a few years, maybe 37 years (yes I'm an old fart).
Steve says his shop has converted more than a thousand (or something like that) but now says DON'T convert. I wonder if he is going to call all those people and have them come back in so he can convert back to R-12 for free since it was the wrong thing to do? haha
I still say, you should never say NEVER when it comes to conversions.

By the way, thanks for the tip on buying R12 on ebay, but I never buy from a person unless I can see him or her in person. The exception is ordering something from a company I know and I called them, not them calling me. Read through some of the post about things people have bought on E-Bay and found out there are crooks everywhere. I know there is a lot of R-12 canisters out there that have propane or a mix in them. I have seen them. The canisters are original R-12 canisters which have been refilled. Yes this is unlawfull but so is robbing banks but it happens every day.

Cigar,

Yes, in the mild summer climates that you have in Canada, I can see how the marginal lack of efficiency from the conversion will allow your system to cool okay. If you would like to test it, bring it on down to Texas and try it on a 108 degree, 80% humidity day.

Even when they cool well, they are typically short lived as Steve says.

pmckechnie,

I'm sure that Steve had the best interest of his customers in mind when he did all those conversions. It is only AFTER he did them and saw the results, plus seeing the cost of R12 decline that he has come to this conclusion.

Also remember, he and his customers are in one of the hottest climates in the US.

I still am flabbergasted at the reasons for many conversions. For Cigar in Canada, he has no choice if he wants to obey the local law. That's a strong reason. For those who don't have such government invasion into their lives, it costs an extra $30 or $40 to use R12 instead of 134. In order to save that much on refrigerant, people often spend a few hundred or more on other things to make the conversion have a better chance of success. I just can't understand that math. Call me dumb.

I have bought lots of things from ebay and have yet to be burned. There is a system there where you can see the feedback from others who have purchased from that particular seller before. If you pay attention to that feedback you can avoid the ripoff artists.

Best of luck to you both,

Larry,

First I was trying to make a joke about Steve recalling all the conversions. I know at the time, he gave them the best he could at a resonable price.
Both of you are so adament about using R-12 that I am going to see if I can find a few lbs and convert mine back. I will take temp readings and pressure readings before and after and let you know how much difference it makes.
My car doesn't have an A\C sticker on it (it has a newer rad support) so I have not been able to get a definate answer as to how much R-12 it should have. Do you have any information on the quanity. I have Alldata and Mitchell and they give different amounts. 2 indes gave me 2 more answers and the dealer a 5th amount. They ranged from a little over 2 lbs to almost 4 lbs. This is an 84 500SEL with a A-6 Harrison compressor (the best ever built as long as the engine has enough power to pull it.)
It may be a week or 2 before I have time to do the conversion. Customers come first.

Thanks and have a great Memoral Day Weekend

300e A/C problems
 

I have read all the above post and find myself in a bad spot. I to converted from R12 to R134 last year after my compressor went out and the new one I bought online was set up for R134. I replaced the reciever/dryer and the expansion valve along with the new compressor, tested it, and then recharged it with 134.
Now my compessor is going out again, I think. just this afternoon it started making noise when I would turn the A/C on. The clutch would engage and then just lock up after about a minute or less. After getting under the car and looking at the compressor, it looks like it might be leaking some mineral oil. But I can't tell from where. It's not like last time where it just blew the seal out of the front of the compressor. It apears to be leaking from somewhere else.
So I guess what I'm asking is, can my compressor be fixed or is it history again? And will this just happen again in a year or so because the system runs at to high of a preseure.
Please help
Shawn
shawnrcisco@yahoo.com

When converting from one refrigerant to another, I've heard it is necessary to change out all O-rings. Does MB use them or only domestics?

Tim

I had to replace my condenser and have my car charged up. In Ontario R12 is not legal for use. The shop that does my heat/AC work is topnotch and has never led me astray in the 10 years I have dealt with them. They only do heat and AC work, on anything that moves. I spoke with Doug about the issues that I have read about on this site and have been reassured that if it is done properly it is not a problem. He got my new condenser, a new dryer, cleaned one switch and replaced another, checked the system for leaks, vacuumed it and then charged it. To date it has worked very well, other than the fact that I needed to replace 4 of my vacuum pods. We have had two periods of extreme humidity with temps in the low to mid 40's, and it worked as well as my Jetta, and better than my Dodge. Perhaps some of the problem systems have not been properly gone over, OR I'm just living life right and mine works.(for now?) Andy

pmckechnie,

Yes, I did not know you were making a joke. Things are easily taken wrong from written text. It's a testament as to the importance of body language.

The chart I have indicates 2.66 pounds of R12 for your '84 500SEL. This is not factory information, but it is probably pretty close.

That said, R12 is not near as fussy about having an exact quantity as is 134. If you get it a little over charged, it will accumulate some in the r/d. If you can achieve about 22 low side and about 250 to 265 high side in 80 degree ambient with a fan in front of the car, engine at about 1500 RPM and after about five minutes for pressures to stabilize, you should be okay.

lyonstexas,

If you change from 12 to 134, you will be better served by using 134 compatible o-rings. These o-rings are good for BOTH 12 and 134. Used to these were green, but now there are 134 compatible o-rings available that are black.

You can get a very good assortment for about$25 from ackits or acsource and it comes with nylog seal lubricant. If you will doing even a small amount of auto air work, this will prove to be a good investment.

Good luck,

IIRC, the problem with the O-rings was caused by the R-134a compatible oil when R-134a was first introduced. After the first year or so, better oils (lubricants, to be more precise) were formulated and are now compatible with all normally used O-rings. That assumes they're in good condition, of course.

Personally, I've converted all of three American cars from R-12 to R-134a. Two were successes, one a disaster. If my 260E starts fading, I think I'll take the silly test and buy R-12 on eBay. Heck, that's how I bought the car.

Cool,

Thanks Larry

Mechanics to recharge R12
 

Try as I may, I cannot locate a shop that will rechange my R12 system in San Francisco. Everyone I ask only talks of the cost to convert to R134. I have a few pounds of R12, no one wants to touch it. I had a few cars with R134, none seem to cool as well as a R12 system. Is this difficulity in locating service shops common in California? Any recommendations.

How to deremine which R12 or R134 system on my 1987 260E (it is not working)?
What is default system for this model? How to find out if the previous owner did not convert it to another system?
Tnx.

Back in '87 a/c was charged with r12 at the factory. If it has been properly converted, it should have the new style fittings (quick-disconnect versus the old 'tire-valve' design). In addition, it should have a conversion sticker displayed conspicuously under the hood.

If you're not sure, take no chances and flush the system some time during the repair to remove the lubricant before recharging.

1987MB260E,

You can go to an automotive a/c shop and they have a refrigerant identifier instrument that can be attached so that you will know for sure. As previously answered, your car was originally R12, but I have seen lots of cars with original fittings that have been illegally and improperly converted to God only knows what. Don't take chances. Have it identified. Not everyone converts them in accordance with the law.

Good luck,

the main reason for converting to R134a is that R12 depletes the ozone layer.

it's about good environmental citizenship, not operating cost.

CRAPOLA!!

Ditto. And even if it does harm the ozone, it only does so if it escapes the system.

To add to Larry's comments, if it's identified as r12, then you can probably assume no conversion was done. But if the refrigerant is identified as HFC-134, you really don't know if the original mineral oil lubricant was flushed out during conversion, and there would be still too many question marks to do anything less than a flush during repair.

So many people asking how many pounds it takes to charge a system. It's not really determined by weight or even pressure, but a fairly straightforward graph that shows the relationship between pressure & temperature in the system.

You can probably "sneak up" on the correct charge by adding refrigerant while the car is running, watching the pressure switches turn on the compresser and then monitoring the temperature of the air being blown into the car. Leak checks are important as is using the correct lube for the refrigerant.

You can read the manual for the certification test for **free** at epatest It explains all this in excruciating detail. The section 609 stuff is for motor vehicles.

Cool,