Ammeter is measuring a voltage across a diode, that was later converted to a current by calibration measurement separately. Diode (actually, two inverse-paralleled diodes) was used instead of a common resistor way of doing it, because resistor will fail to protect the multimeter in case of a spark across the blower. Diodes are very hard to blow open, they typically die blown shorted. These 1A ones survived sparking no problem whatsoever.