Hitachi ZW 370-6 Operator's Manual page 394

IMPORTANT:
 Incorrect installation of the filter may cause dust to
enter into the air conditioner, causing malfunction
or breakdown of the air conditioner.
 Before installing the filter element, clean off dust
around the mounting area; install the filter element
with extra care.
 Keep cab doors closed when operating machine.
3. Install the cleaned fresh air filter or a new filter by
following the filter removal procedure described in step
1 in the reverse order.
MAINTENANCE
7-100