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.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

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

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David McDonald
1981 240D
1985 300D (wrecked)
1985 300TD 365,000 miles
1969 Mustang Fastback

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

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

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.

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84 500 SEL (307,xxx miles)

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!

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

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. 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.

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Old age and treachery will allways overcome youth and skill!

1993 S500
1984 380SL

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

I'm green with envy...here, people have been jailed for illegally importing R12! 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.

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1986 560SL
2002 Toyota Camry
1993 Lexus