Diesel Giant, Larry Bible! Just how how much R134 for a W123 300D?

[Carrameow]

Just how how much R134 for a W123 300D? I've seen it listed with so many different figures I get confused. I was thinking of taking an average of the different values butthat wouldnt be accurate...

[tangofox007]

One a/c expert that I know recommends 85% of the R-12 charge. The R-12 specification should be on a placard near the radiator. (If you can't find that, I will go look at mine.)


My recommendation is that you stay with R-12.

[Diesel Giant]

Please dont use 134a in the MB. Unless you change the condensor to one that is much more efficient and the expansion valve to a matched 134a unit, you will NOT be happy with the cooling.

Either use R-12 or Freeze 12. The pressures are lower, the temps are MUCH colder, and you will be much happier.

[tangofox007]

And converting back to R-12 (from R-134A) is a lot more involved than the 134 conversion. As I am finding out, as I comtemplate going back to R-12.

[Diesel Giant]

All that needs to be done to convert back is the flush the oil out of the system, replace the expansion valve and receiver/drier and unscrew the high and low side adapter fittings. Really not any more work than before. Just be sure to flush ALL the lines and remove the oil from the compressor.

A/C that blows so cold that you must turn the fan switch down is very rewarding.

[didget69]

For the R12 refill, my '84 300D Turbo spec'd 2.2 lbs.

Giant - You mention changing expansion valve out for one matched to 134a; Is there a part number or mfg for this different exp valve? I've never seen one... The expansion valves I've seen locally, including the one I just installed, had R134a stamped on their side; this, however, only refers to the seals being R134a compatible, nothing to do with the valve itself, according to the mfg.

BNC

[tangofox007]

Originally Posted by Diesel Giant

All that needs to be done to convert back is the flush the oil out of the system, replace the expansion valve and receiver/drier and unscrew the high and low side adapter fittings. Really not any more work than before. Just be sure to flush ALL the lines and remove the oil from the compressor.

A/C that blows so cold that you must turn the fan switch down is very rewarding.

From what I have read, it is critical that all of the old oil be removed. And some question as to whether it is even possible to do that. Supposedly, even a trace of old oil can cause problems, perhaps not immediately, but over the long term.
Other than taking the car to an a/c shop, what do you recommend for flushing the hoses, condensor and evaporator. (I will replace the compressor, r/d and exp valve.)

[Pete Burton]

Rich, you should charge your 123 with 1 kg of R12.

[Carrameow]

R12--where are you going to find that these days?????????

[JimmyL]

Originally Posted by Carrameow

R12--where are you going to find that these days?????????

Uh Oh, look out!

[Pete Burton]

Originally Posted by Carrameow

R12--where are you going to find that these days?????????

Some auto parts stores and certainly e-bay. I've bought R-12 in cans twice off e-bay. The last time I got about 6 14 oz cans for about $60. R134a is going for about $10/12 oz can in CT. R12 will work better, at lower pressures, keeping both you and your compressor cooler.

[george d]

I had absolutely no trouble whatsoever. I just took my 1982 240D into a nearby independent A/C shop. R-12 may be a little more expensive, but if the system is working and you have no leaks, it sure does work better.

My MB Independent converted my 1992 190E to R134, and it never worked as well. He did not give me any choice. That's why I went to an A/C shop the next time I needed A/C work done.

George