I'd guess that it is separately switched when the a/c is used but the engine block temp sensor/sender switch that normally switches on the fan has failed. I heard two loud bangs in the rear of my 2005 ...

Sold from the mid 2000s right up until the late 2010s, the Ford Fusion served as Ford’s entry into the competitive midsize sedan segment, aimed at rivals from Japan like the popular Toyota Camry and ...