My dishwasher's detergent cup won't open.

Most detergent dispenser doors are spring loaded. This means that the spring holding the door shut needs to be released by another component. The other component that will allow the dispenser door to open will either be the dishwasher's timer, a bi-metal switch, or a wax motor.

Typical dishwasher timer Timer

As well as controlling cycle times, the timer on many dishwashers also functions as an actuator for the spring-loaded dispenser door. At a certain specific time during the cycle, the timer will activate a lever that in turn opens the detergent cup. If that lever is broken or in some way defective, it will need to be replaced.

Alternatively, the timer's motor itself could be the prblem. If your timer is not functioning properly, then the dispenser door may not function properly either. Test your dishwasher's timer motor, and if it is broken, you can replace either the entire timer assembly or just the timer motor.


Image not currently available Bi-Metal Switch

A bi-metal switch is an electrical component made with two pieces of pliable metal located behind the dishwasher detergent cup. When an electrical circuit is sent to the bi-metal switch, the pieces of metal expand, disengaging the dispenser's door. A defective bi-metal switch will not expand enough to disengage the detergent door. Test your bi-metal switch. If it is defective, you will have to replace it.


Typical dishwasher timer Wax Motor

Instead of a bi-metal switch, many newer dishwashers use a wax motor to disengage the detergent dispenser door. The wax found inside the mechanism heats up to push a piston, which in turn opens the dispenser door. If your dishwasher uses a wax motor, test it. If it is defective, replace it.

Note: A wax motor is tested and replaced in the same manner as a bi-metal switch.