Larry,

When you convert, what all do you replace? Do you just flush the oil and replace seals?

I ask because I have converted 2 German cars and have had excellent results, but when I say "converted" I mean it. New rotary compressor, new parallel flow condenser, new hoses, new receiver/drier, and I always add a new high/low switch.

For most German cars a successful conversion to 134 will require a larger, and/or parallel flow condensor. Tell me. How much R12 can you buy for the cost of a Parallel Flow condensor alone, not to mention the other items?

I've probably written this several dozen times on this forum, but what's one more?

All junk refrigerants such as HC12 and the others fall into one of two categories; a blend or a flammable. I have no idea which category HC12 falls into, but I would be willing to bet big bucks that it falls into one of them.

The problem with flammables is so obvious that I need not elaborate.

The problem with blends is that the multiple components leak at different rates, so if you have a partial loss, the only way to get it right again is to recover the entire charge, and I hope the leak is fixed at that point, and THEN recharge again from scratch. With most blends, one of the components is there to circulate the oil, so you'd best do it right.

With EITHER one of these two categories you have charged the system with a refrigerant that very, VERY few shops if ANY have a recycle machine set up to handle. If they recover it because someone did not put on the correct fittings and labels as required by Federal Law (I trust that you DID use the correct fittings and a label didn't you?) then some unsuspecting shop might accidentally recover a junk refrigerant into a tank of R12 which then contaminants the ENTIRE tank. Not only did they lose the legitimate R12 that was in the tank but they also MUST PAY A DISPOSAL FEE!!!!!!!

This might not happen while YOU own the car, but somewhere down the line you might be responsible for such an episode. Whoever that happens to is just trying to feed their family and put shoes on the baby like everyone else.

If you insist on using junk refrigerant PLEASE use the appropriate fittings and CORRECTLY label the system as to the refrigerant contained inside. Not only would you be complying with the law, but you might very well be doing an honest, proper dealing shop somewhere down the line a favor.

Are we talking about price now? The last PF aluminum condenser I bought was $90 delivered to my door. That's about 3lbs of R-12.

Do you just flush and re-seal? Do you think that may be why you are unhappy with R-134 conversions?

I have done 134 conversions at all different levels from a simple addition of oil, adapter fittings, evac and charge, all the way to changing hoses, condensors, flushing, filter drier, Ester or PAG, yada, yada, yada.

Regardless of the method, the statistics show that converted systems, regardless of how much work or parts were thrown at it, are on the average, short lived.

In the past I converted lots of R12 systems to 134. I have not seen very many of them last for the long term.

Steve Brotherton, who used to post here often, has done hundreds of conversions and kept detailed records on all of them. His conversions were professional and thorough, not simple adapters oil and charge. After time his data, which was much more scientifically kept and analyzed than mine showed the same thing. The average life of even an expensive 134 conversion was a couple of years.

Another member here went through a thorough conversion on a 123 car about four years ago with the determination to build a solid 134 system from scratch. To satisfy his own experimental nature he had a no limit budget with PF condensor, new compressor, hoses, and was even replacing the evaporator at the same time and did some careful work with the aux fan and its controls. After a year or so, he even gave up and reverse converted to R12.

As I said. I have done a number of conversions and some of them have worked out surprisingly well over the long term, but none of the successful ones have been on a German car. If someone today insisted that I convert a system in decent shape to 134 I would still do it as long as they are the sort that will pay their bill, but I would warn them beforehand that statistics are against them.

BTW, if it takes $90 for enough R12 to charge an MB, you are paying too much.

Hydrocarbon refrigerants are not JUNK refrigerants. They have ASTM ratings and are used extensivley in green industrial applications.

It is true that HC12 is both a blend and is flamable. But it is far less of a danger than the gasoline in a gas car. Even a can of hair spray or spray paint is a bigger risk.

The fact that it is a blend allows for more efficient use of the condenser because condensation occurs over a greater length of each tube. Hydrocarbon refrigerants are not only more efficient than other refrigerants usually used in the US, but they leak slower and what does leak is far less harmfull to the environment. Non-hydrocarbon blends usually require one of the components to circulate the oil but they still are rather poor at circulating oil. Most of the hydrocarbon referigerants are inherently superior in oil circulation than even R12. They are also less acitic than R12 or R134a in the presence of moisture.

BTW, Any system with a leak should be evacuated and recharged whether it is a blend or not in order to get the proper oil change.

In many technologically advanced countries around the world, hydrocarbon refrigerants are now the factory charge. They are better for the environment, less strain on the equipment (longer life) and more efficient.

You are correct, you MUST change connectors and properly label the system to prevent cross contamination.

__________________
Ron Schroeder
'85 300 Turbo Diesel 2 tank WVO
'83 300 Turbo Diesel 2 tank WVO
Some former WVO vehicles since ~1980:
'83 Mercedes 240D
'80 Audi 4000D
'83 ISUZU Pup
'70 SAAB 99 with Kubota diesel
'76 Honda Civic with Kubota diesel
'86 Golf
Several diesel generators
All with 2 tank WVO conversion
LI NY

How are you going to correct the oil charge when you evacuate and recharge the refrigerant? Most of the oil stays in the system.

Matt is onto a very legitimate question. If you want to start over with the exact oil charge, you will have to completely dismantle the system and flush EVERYTHING, then start over with a properly distributed amount of oil and a fresh filter/drier.

For most cases that is not a practical solution and if it's only lost part of the charge, you can usually add the correct amount of oil, albeit a bit of a guessing game.

You won't find very many a/c people who evacuate and start over with every leak that they encounter (unless of course they are dealing with a blend in which case it is the only alternative.) If the refrigerant is not a blend, there's no need to.

You did not say that you do indeed use proper fittings and labels for your junk refrigerant conversions. I sure hope you do.

I tell the ac temp from the GF.

Orlando, FL

83 300d r12 hard. Complains I gotta turn the temp up, I complain I'm hot, I keep lookin'

85 300sd 134a not even.

I like r12 better.

R12. For even better performance, consider a high CFM electric fan, parallel flow condenser, and cleaning or replacing the evaporator.

__________________
1980 240d
1999 SL500

More leaves with the evacuation than you might think, but yes, you do need to flush the system too in order to properly add the correct amount of oil. I have lost track of the number of systems that failed a few years after a "repair" that didn't have enough oil replaced.

__________________
Ron Schroeder
'85 300 Turbo Diesel 2 tank WVO
'83 300 Turbo Diesel 2 tank WVO
Some former WVO vehicles since ~1980:
'83 Mercedes 240D
'80 Audi 4000D
'83 ISUZU Pup
'70 SAAB 99 with Kubota diesel
'76 Honda Civic with Kubota diesel
'86 Golf
Several diesel generators
All with 2 tank WVO conversion
LI NY

While we are on the subject of hydrocarbon and non-hydrocarbon refrigerants, would someone please answer this nagging question:

How does a heavier-than-air refrigerant (R12) magically float up into the upper atmosphere and deplete the ozone layer?

Have also become a victim of those stats. Also avoid rebuilt compressors. Mine never worked properly at all right from the start after having it installed with new drier, expansion valve. Next came a new compressor. Cooled remarkably well for a year: 30's-40's, even on 134a. Now in it's second year no longer cools well: 50's-60's and up. Quite tellingly the shop i take it to only gives 6 month warranties on compressors installed into MBs while it gives 1 year on all other cars further backing LarryBible's observations.

Hydrocarbons have the following advantages:
1.Cool as well as R12
2.Won't slam your compressor like 134a does when you turn on ac (visibly less impact on engine rpm) meaning less wear on compressor and less fuel consumption.
3. Won't form corrosive stuff eating away ac innards
4. Works with all oils.
5. Wont leak out as readily.
6. Cheaper -you also need less of it.

Disadvantages:
flammable- only a (mostly theoretical) concern because car ac's haven't been designed with that aspect in mind.
DIY only, in areas where it's not sold and installed by shops.

__________________
'83 SD, 2x '85 SD
You are entitled to your own opinions, you are not entitled to your own facts.

R134 is a scam pushed onto us by lawmakers who were in bed with those who own the R134 patents. R12 was a superior product in every way.

Another really good refrigerant is propane. Cheap and works better even than R12. Do not attempt unless you are a trained HVAC expert though.

__________________
'98 E300 turbodiesel

Yes, my recycle machines have transparent, graduated oil traps so that you can see how much oil was removed so that this can be calculated into the amount that you replace. It is common for as much as a couple of ounces to come out during the recovery cycle.