The W201 190's only had power right side mirror and manual left side mirror. It is possible to add the later W124 E class left and right power side mirrors to the W201, but originally the W201 never came with a power left side mirror.
The switch for changing the adjustable mirror is combined in the mirror adjust button or just above the mirror adjust button (in the same button-square) on all MB models.
The switch ronald mentioned is probably located between his left power window buttons...
we all get power mirrors on BOTH sides...not in the W201...
with a minor 600+k