Ac system rebuild-- synthetic oil R12 to R134a - PeachParts Mercedes-Benz Forum

dmorrison · #1 11-21-2003, 07:06 PM

This is just for discussion.
As you know I'm STILL rebuilding the AC system on the 82 300TD. Lazy IS the word for me lately. I'm trying to finish it up.
I talked to quite a few techs about rebuilding the hoses. They all seemed to recommend NEW hoses vs rebuild. Like the compressor you will be back in a year or two fixing the leaks. The new hoses will last 10-15 years. So Ive decided to order new hoses.
Now everything in the ystem will be new except the high pressure hoses. All the mechanics agreed that the HP hoses were indestructable.
So everything is new. The oil is from ACKITS. It is the synthetec BVA AUTO 100. Good for R12 and R134a. So heres the question.
I put $100 of R12 freon in the system and I find I screwed up and now have a leak. I find the leak, fix it and I leak some more R12, Its now getting expensive.
Could I or would I be able to evacuate the R12 and put R134a in the system without any problems. Now or in the future if R12 goes sky high in price. I now have the synthetic oil in the system so the Mineral/ester oil problem would not be a factor and everything in the system is R12/R134a compatable.
So Discuss or ignor.
I don't know of any reason why I could not switch form R12 to R134a without anything other than recovering the R12. No flushing, no new seals etc.

Dave

leathermang · #2 11-21-2003, 07:26 PM

I am sorry you lost that R-12.... that is one advantage of doing the actual installing at a place that has a recovery unit....
Since the trend is still in our favor here in Texas... I suggest you stick with the R-12 .... after you fix your leak of course...
Did you use any ' sealer' on those seals ? There is a 'thicker' oil used to wipe on the orings and seals... it is the same as what goes inside ( there is one for each refrigerant)... but just thicker is what I have been told... can't think of the name... senior moment...
Which places leaked ? Why did they leak ?
Which color orings did you use ?

Grdenko · #3 11-21-2003, 07:29 PM

its your lucky day, i just spoke to my mechanic about this not 2 hours ago. (looks like my evap coil bit the dust, you can start crying for me now)

.

Quote:

Could I or would I be able to evacuate the R12 and put R134a in the system without any problems. Now or in the future if R12 goes sky high in price.

i asked him, since i might be getting a new evaporator, what would be involved in switching to r134. he said its about 2 hours of labor plus they have to change the condenser filter or something. they have to completely flush the system with nitrogen to get out ALL of the R12 then they can put in R134 sounds like $200. plus, whatever R12 you have left in your system when you start, you can probably sell back to them, if its full, thats around $100.

he also said that R12 probably wont be available in a few years and that if it was, its going to be even more expensive.

i hope this helps.

leathermang · #4 11-21-2003, 07:57 PM

Ok, this has been discussed a little bit.. this particular thread has 234 replies and was viewed ALOT.....

R-12 alternatives

I hate to be cynical.. but your mechanic has an interest in selling a changeover... the people in the thread ( except for REDFOX selling Duracool ) did not...

Each day more of the R-12 cars are sent to that big yard in the sky... and therefor the DEMAND for R-12 may stay low for a good while...

If , here in Texas, your particular car does not satisfy you on the cooling... will your mechanic change it back free ?

Rick Miley · #5 11-21-2003, 08:11 PM

Quote:

Originally posted by dmorrison
I put $100 of R12 freon in the system...

I disagree with this part. How much does the system take? I bought R12 at the auto parts store earlier this year for $18 a can and was told it went on sale for even less a couple weeks later.

You're afraid of it leaking out, but you're going to put the system under deep vacuum for a lomg time before filling it. So any significant leaks would show up then. Granted, things can leak under pressure that don't leak under vacuum, but it won't be a huge leak that will loose all the freon right away.

How close are you to LarryBible? Maybe you could hire him to do the vacuum and fill.

engatwork · #6 11-21-2003, 08:18 PM

Like Rick said - if you can get Larry involved you will have it behind you

. Oh yea - since he works for DC he should be able to get parts AT COST. Anyway, stick with the r12. Look at ebay - 30# containers are going for close to $300 which is, in my opinion, a good price. These cars were designed for r12 and that is what they work best with. Get your on-line certs and pick up a 30# container or r12 and you are set for a VERY long time.

leathermang · #7 11-21-2003, 08:33 PM

You can be in North Texas and still be a good distance from Larry... he is very close to the border of Oklahoma and Texas....

Grdenko · #8 11-21-2003, 08:58 PM

Quote:

If , here in Texas, your particular car does not satisfy you on the cooling... will your mechanic change it back free ?

my dad had it done to his 350SD, and its more than satisfactory, it works just fine, even better than it did on R12. you have every reason to be cynical, probably a good quality when it comes to car repairs, and i wouldn't spend an extra $200-$300 without looking at both sides either.

i have a very good relationship with my mechaic and i consider him a friend (i should, i live 2 doors down from his shop) and he has always served me well, and if he says its a good idea to switch to R134, then im going to take his word for it. i understand that hes still a businessman first, but doesnt he also have an interest in selling me R12 at $100 a fill?

Quote:

Each day more of the R-12 cars are sent to that big yard in the sky... and therefor the DEMAND for R-12 may stay low for a good while...

ok, lets say, hypothetically, that diesel engines were banned from all applications in the US (knock on wood). Then after a number of years each day more and more of them were "sent to that big yard in the sky". Do you think that the price of diesel fuel would go down? do you think that you would even be able to find a station that sold diesel?

its not like there are stockpiles of R12 with people sitting around saying "we gotta get rid of this stuff". production is involved, and if few are buying, few are producing. i dont mean to be defensive or condescending, but i gotta say youre wrong.

dmorrison · #9 11-21-2003, 09:16 PM

Ok let me add some items to the discussion

I have not installed the R12. I am in the process of assembling the system so no R12 has been installed as of yet.

I do live near Larry Bible and I know his outlook on the R12/R134a disscussion. I also believe in the R12 for the 123 cars. the sytem as installed is weak. so by going to a Parallel flow condensor I will boost the capability of the AC system. I also found that aout 50% of the evaporator was blocked by the accumulation of dust and debris over the 22 years the car has been in Texas and Oklahoma.
I willl install R12. But what if I develop leaks. I have a sniffer and can locate any R12 or R134a Leak with the unit. I was just thinking about the switch from R12 to R134a could be done because the oil is synthetic. So not oil problems in the switch over.

Grdenko
I also had the evaporator leak, its a bear of a job getting to the AC box. But doable. My conclusion is to keep R12 if you can. That is what I intend to do. If you are talking about a 123 body. The system is weak at best and going to R134 will make it weaker. In Texas its damn hot and sunny so a good AC system is essential.

leathermang
Yes I will keep R12. Texas is no place to have a so-so AC system.
I also have tinting in the car. It does help quite a lot.

Rick Miley
great to here about the $18 a can. I bought R12 last Jul and it was still $35 at the local parts shop. Where did you get the R12?

OK guys your going back to the R12/R134 change discussion whick has been shot, killled, beaten, tourtured and just plan discussed to death. I prefer R12 for this application. R134 is fine IF the system is designed from the ground up for R134.

So back to the debate.

Dave

Rick Miley · #10 11-21-2003, 10:09 PM

Advance/Discount Auto Parts.

pberku · #11 11-21-2003, 10:34 PM

On my previous car, an '83 SD, I switched from R12 to R134 without doing anything except pulling vacuum on the system and changing the recharging valves, from R12 to R134 Valves. Thats it.

The AC run great until I sold the car 3 years later.

jcyuhn · #12 11-21-2003, 10:47 PM

Dave -

I think I can actually answer your question

I have done the exact same thing in my '87 300TD. Following a compressor seize-up 2+ years ago, I flushed the entire system and replaced the compressor with a junkyard unit. For lubrication I used Polyalpha, an oil being sold by acsource.com at the time. It's a POA, or PAO - a synthetic refrigerant oil which works for both R12 and R134a. I initially ran the system with R134a for a few months because I was nervous about leaks. Once I had things under control, I evacuated the HFC and replaced with R406a - an R12 substitute. No change in the oil required. Everything has been copacetic, system works great (except for the evaporator leak - I'm planning to replace during my holiday break later this year).

So what you're proposing is quite possible, given the right oil. I think BVA is very similar to the oil I'm using, though the viscosity is different. I'm considering using it when I fix (for good) the system in my 300TD.

- JimY

leathermang · #13 11-22-2003, 07:42 AM

Grdenko, I am not saying that YOUR particular mechanic was not truthful or faithful.... I am just saying that in general any mechanic does have a conflict of interests sometimes that they may not even be aware of......
Different cars exist in different states of Efficiency , even if they are the same model and year.... and ' little ' things like the blockage on the fins.... can make or break a ' marginally ' designed system.... I am sure they work GREAT in GERMANY.... but most agree that in Texas heat they need to be at their best for us humans to be comfortable all the time.
Diesel fuel is used by TRUCKS, LOCOMOTIVES, and Farm TRACTORS and possibly could also be used in oil fired heaters for houses in the north.... the banning of consumer automobiles would not eliminate the demand for diesel fuel... but what would be the demand side of the equation if no machines used for cooling existed which were designed for R-12 ? This is not a naturally occuring product pumped out of the ground... it did not exist until the engineers needed it specifically for the requirements of refrigeration. And for those parameters it is as close to perfect as they could manage to create and manufacture.
The key to low cost R-12 purchase right now is to buy it yourself.. not at the local garage.... Ebay or places like Rick found...
When I tried to get my 81 wagon ac fixed about 4 years ago the shop was quoting me $50 a lb for R-12... it is now to where we can buy it for about $20 a lb in car sized quantities, and looks like $10 a lb for larger containers.... until the price trend at least STARTS to go back the other direction I say I am still right about this.
I have seen mulitple 100 degree days in May and we are almost to a late Thanksgiving and it was 81 here yesterday... we have a long period of time here in Texas where we need good cooling to be presentable when we arrive at our destination.

leathermang · #14 11-22-2003, 07:47 AM

pberku , I always find it interesting when people put temperature related statements on the forum without posting where they live... does that make sense ? How are we to evaluate your statement for comparison purposes ?

pberku · #15 11-22-2003, 10:29 AM

Good point. I live in Montreal Canada, where the temperature in the winter can get to -20F, and in the summer to the high 90'sF.

Phil