Are you trying to drive the extruder motor with the hot end cold? If so, most if not all firmware will prevent you from doing that - otherwise you'll either damage something or chew up the filament since filament can't be extruded through a cold hot end. If you're controlling the printer from host software, sending command M302 (allow cold extrude) to the printer should let you test the extruder motor with the hot end at room temp. Of course, you don't want to have filament loaded when you're doing this.