The relay for the power windows and roof is behind the battery (at the right side of the battery under the chassis) and it is black and rather large.
The relay of the comfort locking feature is situated behind the additional fuse box in the trunk. Take out the trunk mat, the black plastic plate behind the spare wheel well (3 "screws") and you will find a white (small) relay being stuck in the plastic cable tray...

greetingz,

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1990 300SL-24
1993 C250D with a minor 600+k kilometer
www.MBenzNL.com(the Netherlands)