The unit has a small tank that is only supposed to be needed when
running in dehumidifying mode. (It even says on the back that the
tank may be completely dry when running in air conditioning mode.)

Unfortunately, when the unit is running in air conditioning mode the
tank fills up in a few hours and the machine shuts off. It orbitally
seemed to work fine. Then I accidentally turned the control to the
dehumidifying selection. Now the tank fills up even when the machine
is not in dehumidifying mode.

The machine is out of warrantee and I don't want to pay for a repair
call just to have the technician tell me that is the way it works.

Is this typical of the DeLonghi air conditioners? If so there should
be a class action suit for false advertising.

Stu