Patent ID: 8540820

Claim:
A method of detecting a rinse aid in a dishwashing cycle, comprising: determining a first turbidity level of fluid in a washing chamber during a rinsing stage of a dishwashing cycle and while the fluid is being sprayed into the washing chamber, generating a control signal to operate a dispenser during the rinsing stage, determining a second turbidity level of fluid in the washing chamber after generation of the control signal and while the fluid is being sprayed into the washing chamber, determining if a rinse aid is present in fluid in the washing chamber based on the first turbidity level and the second turbidity level by: determining whether the second turbidity level is greater than or equal to the first turbidity level, calculating a difference between the second turbidity level and the first turbidity level when the second turbidity level is greater than or equal to the first turbidity level, and concluding the rinse aid is present when the difference between the second turbidity level and the first turbidity level exceeds a predetermined threshold value, and selecting a drying stage of the dishwashing cycle based on whether rinse aid is present.