The city manager, by letter filed with the city clerk, may appoint a qualified administrative officer of the city to be acting city manager during the temporary absence or disability of the city manager. The council may appoint an acting city manager whenever:
A. The city manager fails to make such designation;
B. The council suspends the city manager; or
C. There is a vacancy in the office of city manager. (2002 Code § 2.12.030)