Porsche 928 S 1984 Owner's Manual page 45

Checking refrigerant level
Check the refrigerant level in the reservoir at
least once a year because the fluid diminishes
gradually during operation.
Turn the air conditioner and observe refrige-
rant level through sight glass (arrow) in the
reservoir.
Occasional bubbles are normal.
Foam or a constant stream of bubbles indicate
that the system does not contain enough re-
frigerant.
In case the system requires recharging, con-
tact your Porsche dealer. He has qualified per-
sonnel and the necessary equipment.
42