The following list of relays is from a Mercedes-Benz of North America "Electrical Trouble Shooting Manual Passenger Cars 1975-1979".
There are some numbers, 14, 15 etc. not mentioned in the table, some of the descriptions are not very precise but I hope it's of some use.
(Bought the manual off ebay a few years ago)
RELAY CODE DESIGNATION
Since the exact position of relays varies due to manufacturing convenience, the harness leading to each relay is tagged as a means of identifying each relay. The following listing identifies the code numbering system.
Code Number Function
1 Fuel pump
2 Cold start valve
3 Fuel injection
4 A/C starter
5 Change-over valve
6 Axillary fan
7 Seat belt warning system
8 Change-over valve with additional fan
9 Window regulator
10 Window regulator
11 Starter terminal 50
12 Air conditioning system
13 Headlight cleansing equipment
16 Headlight flasher
17 Carburettor heater
19 EGR/ignition advance
20 Heater coil choke cover
21 Fuel pump relay
koan