You are looking for the 2 relays located to the right hand side of that area behind the battery. The fuel pump relay looks identical to the AC control unit. Usually the fuel pump relay will say kickdown on it. If not look at the other relay and it should say Klima on it if so it is the AC relay and you are looking for the other one!
I can't remember the Part # off the top of my head. Sorry.
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM