My late model Sport 2 #1291 car is only 1 month old and 1,000 miles. In week 1 of having the car the sensor for the coolant temp of the battery failed. NY service replaced right away. Since then I have the same overheated PEM you are describing. Aftet letting the car sit and cool overnight without charging, the PEM is on the 4rth light before I leave my driveway, and in the first yellow another block farther. I constantly get the reduced power message while driving, and I get the "will take longer to charge due to excessive temperature" when charging. No way this is from gunk in the fan, or salt. Logs show that the culprit may be an errant temperature sensor in the PEM, so the fan is not getting the instruction to turn on. Service ordered a new PEM and will install next week when it comes in from California.
Now I understand why the Roadster was the guinea pig car for true enthusiasts willing to put up with this stuff. Despite amazing service responsiveness I doubt mass market consumers will accept these problems on Model S, and Tesla would get a bad name. They will not get credit for pushing the technology, being a leader, or anything if there are widespread problems. That said I wold hope they put a filter in the Model S.
In looking at the photos of corroded fans I wonder if the solution is to replace the bearings alone. Used sealed bearings made for heavy use. The photos look like the bearings are open body units and salt and crud can enter the bearings themselves.
