My first attempt to convert our 1988 W124 wagon (black w/black tint windows) from R12 to R134a, wasn't very successfull.

We only changed out receiver/dryer; expansion valve; and pressure switch, drained oil, and refilled 80% with R134a and the proper oil. On a 95-F trip to Las Vegas it cooled down to about 78-80 F.

This time, we evacuated everything, replaced the single pusher AC fan with the dual AC fans from a 1990+ W124 R134a vehicle, as well as the R134a specific condenser.

Also, replaced the viscous fan with a 16-inch SPAL puller fan at 2370 CFM.

Our trip to Las Vegas in 95-F cooled the cabin to a very cool 65-F.

In short, get more airflow with electric fans, and a high-flow/high-density condenser.

:-) neil

JCE, and others, Yall are doing a great job on this...

Manufacturers are able to say things that are technically true but that do not take into consideration all the conditions which may exist when the product is being used... for instance... FLOUR,,, plain old baking flour... does not burn easily... but you only have to see one grain elevator explode from a static electricity spark igniting the flour dust to realize that real world physics is a serious subject....

Thanks to all for taking the time to expound on this subject so well... Greg

I emailed the company with more details of our discussion:

"1-2 lbs cannot actually compress inside the
cab of a merc. That couldn't even happen in Volks bug. That much could fit in a little can. Even if you designed an impossible leak which pumped, purposely every oz. into your cab with the
windows up, your entire family could still sit in that cab holding lit
candles."

"I am sure that all involved are just trying to be safe and we applaud that. be assured that hydrocarbons are safe. See the extensive work performed by Dr. Ian Maclaine-Cross of the University of New South Wales. He calls such scenarios impossible. It's as simple as that"

They sure did blow that 116 body up using freeze 12. Anyway the point is you get what you pay for so there is no miracle low price freon. You do the job right the first time or you work on it year after year . Logically it would be less expensive to fix the system properly the first time . Like I have said before ask the techs they have the most experience in this field. I can gaurantee the techs that have worked on mercedes most of their lives will tell you to stay away from this junk.

__________________
euro 287
Mercedes Technician 7 Years (retired to Hyundai)
2000 Dodge Durango
98 Mazda truck

This is pointless. A compressed gas does not COMPRESS into a larger (lower pressure) volume, it EXPANDS into that volume. A compressed refrigerant will expand and difuse into ANY size lower pressure volume. If by no other mechanism than Brownian motion, it could expand throughout infinity, in theory.

When, during that expansion, a flammable compressed gas falls within it's LEL/UEL concentration range, it is a flammable or explosive mixture. The presence of non flammable gas may or may not be sufficient to permit that mixture from forming. I would presume that in the case of Freeze 12 it doesn't form or forms with such low probability that EPA allows it on the approved list.

I have not at any point stated that Freeze 12 isn't safe. If the EPA is happy with it, after consulting lots more than 1 researcher, then everyone is happy. If the EPA is unhappy with most automotive hydrocarbon based refrigerant applications (again, after consulting lots more than 1 researcher, and with public comment review, and National Science Foundation oversight committees, and peer review process) then maybe you ought to listen to them regarding pure hydrocarbon refrigerants instead of the people making money from the sale of pure hydrocarbon products.

The cigarette companies could find a minority of researchers 'proving' that their products are safe. But Science is done by majority consensus approval of all data. 'Facts' are accepted as truths until something blows them out of the water. Dissent is part of human nature, and people still calculate the value of pi, re-calculate the atomic weigh of Hydrogen, and debate 'established facts'.

Despite debate over the details, gravity still pulls, and Propane still burns, (and may explode) - it is that simple. It may not burn if other gases keep it so diluted that it can't fall within the LEL/UEL levels of concentration, or if no spark is present, etc. You can NOT safely extrapolate the safety evaluation for one mix of gasses approved for one application to every (or any) other mix of gases, pure gas, or different application. EPA, OSHA, NFPA, etc are in the hazards evaluation business. I did chemical, radiation, and biosafety hazards evaluations for 25 years, but if you are happiest with what the manufacturer says, then live long and prosper, for you have found Vulcan Kohlinahr, and need no other commentary. Nuff said.

__________________
John

2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)

Click to see 87 300E

If you look at JCEs profile, you'll see that he's a retired physicist.

That's close enough for me.

JCE - thanks for your input.

hey, just passing along their comments, perhaps its useful to see how these parties react to such questioning. I did invite the individuals from that company to respond for themselves here but in their absence i provide what they have emailed me.

No problems or bruised ego on this end. Maybe a little to forceful in making my point that manufacturers need to stay in business, and that the MSDS is a more reliable representation of facts about a product than web sites or sales brochures. You will make a choice that works best for you, and that is all that is needed. Enjoy the day!

__________________
John

2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)

Click to see 87 300E

JCE, I don't think you were too forceful at all, and I have been saying you were doing a great job on this subject...

Now, as John Lithgow says on Third Rock From the Sun " Lets get back to talking about ME "

So far.. in trying to overcome the physics challenged 134 cooling abilities compared to 12... I have come up with this list:

1. Be sure to be using the 9 bladed engine fan.
2. Use the parallel flow condenser.
3. Be sure the system is charged properly.
4. Use a bigger AC assist electric fan in front.
5. 134 Expansion valve (thanks Joe)

6. ?????????? Any thing else ???????????

Thanks, Greg

I've taken 2 of my old wagons, (88 124 and 85 123) and simply evacuated the systems, swapped out to 134 exp valves, replaced the driers and o-rings and blown in 134. With ester100 of course. I charge them a little different tho', start at 50% which is about 12 OZ and slowly blow in the rest looking for the lowest temp at the center vent, windows closed, recirc door closed and car fully warmed up. The 88 wagon in a shop that was about 85 deg F at the time worked itself to 44 deg F and Tom just took it to Texas and said it maintained 44 to 48 the entire trip. The 85 made it to 50 and maintains it well except sitting in traffic if the temp is over 90, it'll get into the high 50's then.

No changed were made to the basic system other than expansion valves. I did however seal the condenser to the radiator as well as I could.

On a 'nother note, I converted a 92 Lexus ls400 today (and guess what, it needed a evap) and it made it down to 48 inside the shop and today it was 95 deg in there when I charged it.

One BIG issue I've seen over and over are oil flooded systems and 134 systems seem to be particually sensitive to this problem. 2 OZ too much oil can raise output temps 15 deg's depending on the size of the system. Both of the wagons already had the red pressure switches for the aux fans so they were left alone.

134 aint a straight up replacement for good old 12 but, it'll do a decent job provided you run a 134 expansion valve, be sure not to oil flood the system and ignore that damn sight glass while charging. (I've noticed that around 2600 rpm the glass will clear on the ones I've charged by temp and paid attention to.)

One trick I use as well is superheat, put a temp probe on the suction line right at the expansion valve and charge it untill the the temp at that point is about 38F, the high side will be in the 240F zone at that point. Dont forget the old rule of thumb, on fresh air intake output temps that are 30 deg's lower are acceptable. And I've seen some that would barely do 20.

I'd run from the off the wall stuff due to too damn many potential problems with flammability and performance over the long haul. And a quick remark to the guy who feels shops overcharge for r12, bought a reclaimer lately? They aint cheap.


Joe

__________________
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364

I've been reading this thread with great interest as I want to convert my W123 over to 134a. Some of you who have written on this thread have experience doing conversions. I'm not interested in hearing about "alternative" methods.....only R-12 to R-134A. So please keep the topic to 134A and not go off on these other ones.

Questions:

1) Does a person really need a parallel flow condenser?

2) What parts SHOULD be replaced when converting over to 134A?

3) Since my AC system isn't working right now, can anyone tell me if the aux fan is supposed to run when the AC is turned on? (240D without ACCS)

4) Any tips or advice from those who have done this would be great. I assume that the DIY can do this job without killing oneself. I guess what would be really great is if someone could run down the basic procedure of how to do this. Summer is coming and it gets into the 100s here in central California.

Thanks for the info.
mike

JOE P: Can you tell me exactly how much oil I should put in my '84 300D when I convert to 134a? And about how much gas?

MRWITH: Here is a quick review of what you need to convert to r-134a:

PARTS: all new (green) o-rings, new receiver drier, expansion valve, 134a-specific valves that screw on top of the r-12 shrader valves (I'm refering the valves with which you evacuate and fill the system), cans of gas, a bottle of oil

THINGS TO KEEP IN MIND:

-no matter how successful an r-12 system is converted, 134a will never perform all that well sitting in traffic. You won't start sweating, but you probably won't feel cold either.

- for lots of general information on this topic, start searching www.aircondition.com, which is a terrific webpage on automotive a/c

-the sponsors of this page, airsource.com and ackits.com, sell everything you need for your a/c system and are extremely knowledgeable

-one of these sources has rebuilt r-4 compressors for $134! Keep in mind that your compressor that has run for years on r-12 probably will not last long on 134a. THis is a somewhat debated issue, but the fact is, 134 does require higher operating pressures, and if your compressor is the least bit weakened with age or wear, you will find that it can't keep up with system demands, and the end result is you have bad a/c, and you are sitting there wondering what went wrong. I would just replace your compressor. If your system already doesn't work, it is probably already bad, if not just from sitting there from lack of use and oil starvation.

-DO NOT try to do this job without a proper vacuum pump and gauages. I happend to pick these items up cheap through the local paper, but a vacuum pump that will actually do the job costs around $300 new, and a set of gauges can be picked up at Pep Boys for around $50.

-Because you probably don't want to go to the expense of buying the pump and the gauges, I would recommend you replace all the components yourself, and then take it to a shop to have a vacuum put on it and filled with gas. Maybe you can check a local rental store to see if they have a vacuum pump??? If you are in the DC area I would let you borrow mine.

-As someone else mentioned, ignore the sight glass completely, it means nothing!!!! With a/c systems, the ONLY thing that means anything are the high and low side operating pressures. And this is why gauges are vital. You CAN NOT do real work on any car's a/c system without gauges. Generally speaking, you are looking for pressures around 180-190 high side and 30-40 low. But these pressures vary depending on the car and outside temperatures. High side pressures should be around 2.5 times outside, ambient temperature. Too high=poor cooling and death to your compressor, too low=poor cooling. Bottom line is? Get gauges, don't try to guess, and ignore that sight glass!

-in order to do the job right you need to blow out every component with a blow gun and mineral spirits. After you have blown the mineral spirits through and made sure it is comming out clean, blow just air through for a while to make sure all the mineral spirits are blown out and the component is dry.

-the best oil out there for a completely clean system with a new or rebuilt compressor is a Texaco HFC100. Get it at ackits.com. If you are using your old compressor with 134a, use PAG oil, NOT ester oil. The oils can be injected into the system with a turkey baster. All the o-rings need to be coated with the oil before installed.

-lastly, you do NOT need a parallel flow condensor. This was just my suggestion to the guy asking how he can optimize his system, but that is not to say your original condensor won't work too.

I think I covered everything. If there are any more questions, I will try to answer them, but you should really start going to aircondition.com, which is where I have collected most of my information.

One last fantastic info source is this saab technician's page (I am somewhat of a Saab feak too :

http://216.78.172.244/climate_control_folder/ac_retro.htm

and

http://216.78.172.244/climate_control_folder/acpressurediagnosis.htm

Hope this all helps.

Greg
'84 300D

Greg, great info...How many green oring seals are we talking about on your car ? Did you have to take the evaporator out from under the dash to install the 134 expansion valve ?

After flushing with any non 134 liquid I would suggest flushing with which ever type oil will finally be in the system until it also comes out clean... and keep blowing air until all of it comes out that will reasonbly come out.... Mineral Spirits , etc may have things which as residue would form gunk or acids...etc.... Thanks, Greg

123 exp valves are easy to get at, right under the r/h dash, just pull off the plastic trim and look up. I've seen a few oddball aftermarket systems that had parts in weird places but, most are right there.

4 o rings on the valve, 3 or 4 on the dryer, 2 or 3 on the condenser, most 123's use the York piston type compressor with the taperfit lines, no o rings, there are a few line joints under the hood that have o rings in them, replace them as well.

My wagon cooled well with the high side at 210 psi lo side at 33 psi, idle. The red switch throws the aux fan on around 225 psi which mine hit after 3 or 4 minites of idle. I ended up with 2 OZ of ester 100 in the dryer and thats all the oil that went in, if you's like, remove and drain the compresser, measure the oil that came out and replace with ester, same deal with the condenser. (most condensers hold 2 OZ except the monster in the 140 that holds almost 3)

I ended up with about 22 OZ of 134 in the 85. There again this is dependant on abient temps, air flow, evap size, condensor size and line lenght. Make sure the AUX fans work and your fan clutch is in decent shape. There again, I'd seal the condenser the the radiator as best as can be done without blocking the airflow over the radiator. (those little rubber seals on the 201 are great for this)

I've heard the storys about hoses that wick 134 through the walls and have never seen one leak that way with 134 unless it did it with 12 as well. Dont flip if you see 300 psi Hi side pressures as long as it dosen't get past that very far, if you freewheel the motor to 4 grand and it stays under 325, it'll be fine as long as your hoses are ok.


Joe

__________________
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364

I'm going to buy a rebuilt R-4 compressor when I fix the ac system. My question is whether or not the new (rebuilt) unit will have oil (the kind used for 134A) in it already? Or, do they send them "dry" from the factory?

One last question. How does the Aux fan work with these A/C systems (W123 with R-4 and no ACCS)?