c126 air con charging adapters?

[Somebody]

So, I came to another dead end, and need your peopleses help.

My 126 is scheduled for its air conditioning maintenance run, but the air con tech dude took the valve cover off and looked confused. He then said that although they stock the correct gas/chemicals to retrofit into older cars, they don't have the correct adapters to connect a modern air con maintenance/charging station to that system.

So then came the adventure of finding somewhere that stocks these adapters.

So far, nothing. Even Benz themselves have no clue (thats not unusual).

Somebody gave me some part numbers for some old retrofit kit, but I looked in some ancient catalog my buddy had, and those numbers correlate to 1/4inch imperial fittings. I assume a Benz cannot possibly have imperial ANYTHING apart from tire diameter and seat belt bolts, which are imperial in almost all cars.

So, can anybody please enlighten me? Where the hell can I get adapters to hook that thing up to a modern air con maintenance station? Or if you don't know a specific product, can anybody at least tell me some specs, like what threads they use etc?

This is annoying.

 

[jaymanek]

Very easy

http://bit.ly/1jFyPDD

If that link doesn't work search for r12 to r134 on eBay.

Local hose places also stock the adaptors.

 

[Somebody]

So, let me get this straight (sorry, I really don't know nothing about air con systems at all).

R134A is not only the name of a chemical, but also the name of the connector union style? So, all modern air con maintenance/charging terminals, the kind they have at most auto repair shops, are called R134A, not only because its the primary chemical they pump, but also because it's their connector style.

And R12, again, is not only a chemical, but also a different older connector union style? Threaded instead of clip-on Like mine?

So my car has R12 unions?

I see all the R12 unions on ebay are either 3/16'' or 1/4'', which is exactly what the dude told me when I looked in the old catalog, that It will be 3/16 or 1/4. So could it be that imperial fasteners survived just out of compatibility even on Euro cars?

Thanks!

 

[jaymanek]

Yes so basically R12 gas was in use until the early 90's and they had the older style connectors on them.. Then R134 came in and they used the new adaptors so that the gasses couldnt be mixed.

R12 runs a lot cooler than R134.

Remember that when you fill the gas, the R134 weight is 80% of the R12 weight of gas required.

Your car should still have R12 screw in type unions unless its had some other conversion!

I have to warn you though, its very likely that after some time you will find your system leaks, normally at the condensor. I have had to replace condensors and driers on all of my cars now after doing the change over.

To add to the complication, some specialist A/C places offer an R12 replacement gas which is supposed to be as cool as R12 but environmentally friendly... I have no experience of this though.

 

[Somebody]

Thanks for your help. Now after a day of headaches, I finally got to the bottom of this. I now found the correct adapters.

It seems that R12 connectors are a strange and mysterious thing, because:

-Like seat belt bolts, they are imperial threads. Even in the 80s and 90s on Euro cars!

-They are one of those strange connectors that's called a number which does not relate to it's thread size. So a connector called 1/4 inch actually measures just over 11mm or 3/16inch in real life. Thats what was confusing me before.

-You need to empty/vac your gas system and then remove the stock valve cores in order to fit the adapters, which have their own cores. They will not just fit over the old connectors without removing their cores first. That confused me and the air con engineer person for a good 10 mins...

It seems the current most popular retrofit gas fill is hydrocarbon based. Its supposed to be better than R12 because its not restricted, and also better than 134A since it works better, and compatible with both systems, and also for the environmentally conscious types its not environmentally harmful either.

So I got some adapters and all is well. Now I just need to figure out which stub is low pressure and which stub is high pressure. I think the one by the front of the engine bay, the smaller pipe, is high pressure, and the one nearer to the firewall, the bigger pipe, is low pressure. But I should probably make sure just in case. Anyone know?

Will let you know how I get on with the leak test.

Thanks for your help.