What are fuses doing in the relay box???
 

I cracked open my relay box on my 87 w124 and found two fuse holders (one occupied and the other empty). What are these for, and what rating fuse should I put in the empty fuse holder (if at all)? Haynes and the Mercedes Bible haven't shone any light to what they are. Thanks!

Should be listed on the fuse chart. I wouldn't put one in the other side. On the fuse chart I think it'll say "aux fuse holder" or like that. Am fairly sure related to climate control.
Gilly

If you're that curious, pull the fuse out and see what stops working. ;)

fuses
 

Both fuse locations are supposed to be for the alarm system. On my car, the second slot was also blank but the alarm still works.

Alarm system
 

That would make sense considering you have to unscrew the box to get access to it. If the alarm fuses were in the fuse box, a thief would just have to pop the box open and remove the correct fuse. Thanks!