Olivetti PG L2555 Service Manual page 138

(4) Direction of installing the principal fan motors
When detaching or refitting the fan motor, be careful of the airflow direction (intake or exhaust).
Power source fan motor
(Rating label: inside)
Intake
Developer fan motor
(Rating label: inside)
Intake
Intake
LSU fan motor
(Rating label: inside)
Figure 1-5-51
1-5-31