Zafer-- more info --
I just got a post from an anonymous party that claims there is a low
pressure port on or near the accumulator (the silver colored cylinder in
front of the evaporator housing). He also said that a closer reading of
the manual suggests topping up the system after a simple test of feeling
the temperature in a few places.
PS - I've got some more reading to do tonight!
PPS - He also made the excellent suggestion of visiting the public library.