There are 2 speeds & 2 relays that control the fans, from the sound of it one of the fan relays have a blown fuse. The relays are under the rear section of the fuse box (under hood). Look for BLUE relay.

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MERCEDES BENZ MASTER GUILD TECHNICIAN
ASE MASTER TECHNICIAN
27 YEARS DEALER M.B. Shopforeman
190E 2.3 ITS RACECAR
1986 190E 16V