Ac fan mode power consumption is lower because the compressor is shut off. The air condition is not generating chill air but you are getting ventilation which supports lower temperature by a few degrees.
You also need to know how the fan lowers the temp like an AC. Most cooling fans will have motors that build pressure on the intake air and force it out through the blades (or bladeless in some models) to add more airflow and a cooling effect to the air it moves.
Vialetter has an amazing range of well-built and affordable compact fans (AC and DC) that are efficient and quiet while moving large volumes of air to keep your computer cool. We offer axial and brushless fans in a variety of common sizes (up to 120 x 120 x 25.5 mm) to meet your specifications. These durable fans have a 50,000-hour life expectancy and feature a heavy-duty aluminum frame with glass-reinforced thermoplastic impellers. You won't find this quality anywhere else at such a low price.