The 94/95-124 chassis have a fuse on top of each relay.
The high speed is a 15, but has been updated to a 25, and the low speed [ a/c pressure ] is a 30 A.
On the E320s , the high speed relay is blue [ slot C behind fuse box], the low is green [ slot B ]. This may differ on the E420, as the relays are switched in the CD.
One would think that the 30A circuit would be high fan, but the low fan circuit is the 30A due to the series resistor draw.