Why does your ford f 150 smell like fish when ac is on?

If your Ford F-150 smells like fish when the AC is on, it could be due to mold or mildew buildup in the air conditioning system. This often happens when moisture accumulates in the AC evaporator, creating an environment conducive to bacterial growth. Another possibility is that a foreign object, like a dead animal, is trapped in the ducts. It's advisable to have the system inspected and cleaned to eliminate the odor.