Another case of Legionnaires' disease has been reported over the weekend.
In the past few months, there have been 13 cases of the illness in Auckland, one of them fatal.
The Auckland Public Health Service says health officials are trying to find out whether the latest case of the disease is connected to others which have been reported recently.
The legionella bacteria that causes the illness is often found in air conditioning cooling-towers.
The Health Service says it is exploring all potential sources, including car wash systems.
Last week, the Auckland Council sent 15,000 letters to businesses asking them to treat cooling-towers with chemicals immediately to combat the bacteria.
