A malfunctioning HVAC blower motor regulator can cause the blower motor to operate below the requested speed or not at all. Updated regulators are available; the blower motor and cover need to be replaced at the same time to upgrade the system.
Car Problem Reports
Mercedes-Benz E430 Malfunctioning Regulators May Cause Blower Motor Failure
Mercedes-Benz E430 Problem
Average Mileage: 134,500 mi (124,000 mi - 145,000 mi)
Visitor, 1998 Mercedes-Benz E430, 145,000 mi
The blower fan will sometimes work at full speed and sometimes it won't. The blower operates on low speed but will not switch to high in either auto or manual mode... most of the time. Whe the problem first apperaed it would come on at full blasr when the car was first stated then quickly reduce to low speen. Now it seems to be in low speed all of the time. No fix yet.