HP Compaq Presario,Presario R4000 Maintenance And Service Manual page 140

Removal and Replacement Procedures
3. Remove the three PM2.0×4.0 coarse screws 1 that secure the
fan to the base enclosure.
✎
The screws removed in Step 3 have a coarser thread than other
PM2.0×4.0 screws used in the notebook.
4. Remove the fan assembly 2.
Removing the Fan Assembly
Reverse the above procedure to install the fan assembly.
5–50 Maintenance and Service Guide