Yup, I remember that thread. Still haven't done the total a/c changeout on my 124 wagon; wish I had that kind of time to tinker.

While a parallel condensor is a big step forward, there is still one problem area on many older mercedes. Depending on the compressor used, there is simply no way to get really cold air at idle. This particularly seems to be a problem in cars which use the Nippondenso 10P15C compressor. It just doesn't "put out" enough at idle to adequately cool the air. Simply put, the amount of liquid refrigerant delivered to the evaporator isn't sufficient to fully cool the airflow.

I think dual receiver/dryers would be an interesting trick. I would not expect such a setup to deliver any cooler temperatures driving down the road. However, they might help with idle performance. The R/D is also a fluid reservoir - it stores liquid refrigerant until called for by the expansion valve. Adding a second R/D would essentially double the quantity of stored liquid refrigerant. I expect the vent temps would stay cold for a longer time at idle - until the contents of both R/Ds were exhausted.

- JimY