240 r12 > r134a conversion?

[farewelltoernest]

Well, summer is coming up here an arizona, and fortunately for me, my 240DL has a freon leak!
Now, the previous owner of my brick has some AC service done in July of '09 according to a sticker under my hood.. However I have no idea what was repaired, or if the conversion was done then.

as far as the little diagnostic part near the passenger side headlights goes, everything seems to look original (except for the diag port itself, which is probably the cleanest thing under the hood). The reason I believe a freon leak is present is due to the bubbles that pass through the diag window when running the car with max AC.
Now, I'd like to believe that's the whole problem, but I don't know for sure. So here are my symptoms:

AC takes a few minutes to get started but then blows pretty cold, but only for about 20 minutes, after which It just blows warm air through the cabin. This time will be extended slightly if I am freeway driving. Now if I leave the AC on and continue to drive the cold air will come back, but for a shorter period of time.

Anyway, I could just use some advice on the conversion and whatever else could be going on. All advice is very much appreciated.


-Kyle

 

[jerryc]

there is a comprehensive how-to for 7/9 on BB. While not directly related, I think it'd offer you some insights. I did it once and have another car it was done to, and it can work.
The system has to be vacuumed to get any moisture out. This should also find out if there are leaks. The oils for R12 and R134 are incompatible so when you put in the new stuff the right amount of the right oil has to go in also. Oh, and the compressor should be drained also first.
Then put in the right amount of R134 and it should work.

 

[Cabrioman]

Okay, this here is for Europe (EU). I don't know, what is allowed and what is forbidden in the USA.

There is a replacement for R12, where you have not such an effort:
R413a ("R" - fourhundredthirteen - "a"). It is more a "insider-tip", I think.

For R134a ("hundredthirtyfour" - to avoid mixing ) normally you need a change of different parts, gaskets, etc... And a flush finally... That's expensive (work, parts).
In addition: here in the EU, I've heard, that R134a is going to be abandoned as well in a few years! So it is more than useless - or next to fraud, if someone here gets a recommendation for a change "R12 into R134a". In some years the owners of an oldtimer will be confronted with the same problems. But this is kind of lobbyism from the industry....

The best experiences here made the guys with R413a. It is difficult to get. Here it is used in factories or cooling units for big truck-trailers. Look for big industry demand or trailer-services.

 

[JohnMc]

There are various R12 replacements here, the only thing better about an R134a conversion is that if you need an occsional can to top the system off (slow leak) then they're in all the lcoal auto stores for cheap.

 

[vvpete]

In Arizona, I wouldn't convert from R12, just get it fixed. This is especially true for 240's before 1990 that has smaller condensers, evaporators, and use the expansion valve (it is always a good idea to tell us the year of your 240, as there are different solutions for the 4 or 5 different A/C systems used in the 240 over the years).
If you have a 1991-1993 240 then I would say do the conversion, otherwise buy R12.
Since you're in Ariz, contact ACKits.com. They are in Phoenix and have expert opinion and great prices on parts.