Speaking of wiring, I am working on a 95 E420 with an A/C not cooling well complaint.
Testing revealed that the A/C was cycling on and off due to high pressures and the fans weren't on. Turns out the 18ga wire going to the stage one blower resister burned in two at one end of the resistor. The resistor connector appears loose and causing the extra resistance to heat the area, but the wire burned in two not the connector.
This would of failed differently a few years ago when they put real wires on these vehicles.