Hello!
You are getting exactly 162.5 Pa delta pressure because of the fan boundary condition definition:
The simulation is calculating a flow rate < 0.69 m3/s and you are requesting this to be 162.5 Pa given the advanced settings of the curve definition. You can either provide more data points for lower flow rates (like in this definition) or change the out of bounds definition.
PS: the flow domains are fairly short in the flow direction at the moment.