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...

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.

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.

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

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.

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.

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

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

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.)