Before installing new regulator, check heater motor for current draw. 99% of electronic speed regulators fail because of heater motor excessive current draw.
To check heater motor draw, place clamp meter (part no 991 600) over the battery cable.
Turn ignition on, note the current draw. Turn the heater to defrost positon and note the current draw. If the difference between two mesurments is above one sepcified by the manufacturer, new blower regulator will fail shortly after installation. Heater motors generaly use 4-25A (50-300W).