NEC NP4001 - Manual (Page 116)

6. Maintenance
104
3.
The rear filter can be
accessed as shown.
Once the filters are cleaned, please reset the filter hours via the Clear Filter Hours op-
tion in the v Reset Menu Descriptions and Functions on page
101 .
Note:
Using the projector without the air filter fitted inside, dirt and dust are sucked into
the projector, causing failure.