In a thermal design of compact electronic equipment, the estimation of cooling air flow rate is essential. This paper deals with an experimental study for performance evaluation of cooling fans, in case when obstacles modeling a high-density packing condition are placed around a fan or the inlet of a package is partially closed, aiming to shed a light on the relationship between flow rate and flow condition near intake region of a cooling fan. It is shown that the pressure difference between the front and rear of a fan should be evaluated carefully, when the shape of a flow passage changes abruptly in front of a cooling fan.