Do both cooling fans on a Chevy lumina 98 run at the same time?

No, the two cooling fans on a 1998 Chevy Lumina typically don't run at the same time *all the time*. They are controlled by the PCM (Powertrain Control Module) based on engine temperature and other factors. One fan might run alone at lower temperatures, while both fans engage at higher temperatures or under heavy loads to provide sufficient cooling.