On the expansion valve, the A 210... is the new version and the A 202 the older one. But I doubt that is the problem. In early models of W210 EC light on could be faulty temp sensor (moisture and corrosion) or low refrigerant level. Design of sensor was changed to correct the problem but I don't know exactly when.

From what little I know, it sounds like blockage somewhere. Since you've got a new drier coming, might as well wait and see it that's it. If the A/C system has worked well for 147K without repair then I'd say a few issues isn't too bad.

Good luck.