[cdrptrks]

Yes you have to remove the seat(s) from the car. Cover the door sill with a towel or something to prevent scratches.

If your car was built during the time where there were supply chain issues, you should probably check to make sure the fan is actually there under the seat(s) before ordering the wiring kit to be safe since it is not an advertised feature on the 1SS 1LE.