This is the relay table for a euro 1988 928s4 automatic.
(relays and functions do differ per year I'm afraid)
A commonly used relay in a 928 is the 53 model. Here is some detailed info.
Parts: Relay
OEM: 141 951 253 B
431 951 253 H
443 951 253 K
8D0 951 253 A
Make: AUDI VOLKSWAGEN
Remarks:
For:Electric fan 40A,12V 4-pole