The fans and air conditioners quit working for thousands of Davenport residents last night. So did everything else — as the power went out about 6:30 P-M. MidAmerican Energy spokesman Kevin Waetke says there was an equipment failure at a substation.Waetke says the power was restored to some seven thousand customers within two hours. He’s not sure yet on what caused the equipment failure, and says there’s -no- mention in the service report that it was heat-related.