Originally Posted by shbox.com

There are two versions of the dual fan configuration:


1993-1994 - Primary and Secondary fans that operate at only one speed. When initially commanded on, only the primary fan (driver side) comes on. It operates alone at full speed. If the temp threshold is met for addtional cooling, the secondary fan (passenger side) also is commanded on. At this point, both fans are running at full speed.
These fans use a two relay architecture that can be seen in the fuse/relay panel that is under the hood.


In late 1994 and into 1995, there was a change to low and high speed fans. When initially commanded on, both fans will come on at a low speed. When the high speed temp threshold is met, they both bump up to high speed. A three relay architecture is used for this fan version (seen in the fuse/relay panel). By adding a third relay, low speed can be achieved by running the power to the fans in series. This way, each fan does not get full voltage and runs at a slower speed. High speed happens when the relays switch to provide full voltage to both fans. Low speed is less noisy and should result in greater fan longevity. High speed is not always needed.