The Porsche cooling fans in a 928S4 GT or GTS model are operated by a power stage that often fails after many years of service. Symptoms are running full power, one fan always runs full power while the other fails, or fans not running at all. We repair the fan power stage and make it run withing specs again. Repair involves sending in the broken unit and get a replacement unit in return. Two options: have your own power stage repaired, or purchase a repaired one (no core needed). We provide a full functionality check and 1 year of warranty on our repairs.