Dell Vostro 14 3430 Owner's Manual page 54

Steps
1. Place the fan in the slot on the palm-rest and keyboard assembly.
2. Align the screw holes on the fan to the screw holes on the palm-rest and keyboard assembly.
3. Replace the two screws (M2x5) to secure the fan to the palm-rest and keyboard assembly.
4. Connect the fan cable to the connector on the system board.
Next steps
1. Install the base cover.
2. Follow the procedure in After working inside your computer.
54 Removing and installing Customer Replaceable Units (CRUs)