Yeah, it does have 134a OE from the factory, but no dust / pollen filters. Strange, but true.
I also have been notorious for disseminating bad information that r134a therefore appeared on Mercedes starting from 1993 model year cars, but every 1992 500E (3 of them, all today at the GTG in San Diego) I've seen with my own two eyes has come with factory 134a.
I do know that 1992 300E's did not come with r134a, but I don't know about 1992 400E's.
We'll just have to ask an owner of a 92 400E about the disposition of their factory a/c, won't we?
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".