There is no defrost timer in your refrigerator. The defrost operates by the control board (#5 at the diagram
You have to check the defrost heater and defrost thermostat (#10 & #14 at the diagram
) for continuity. The defrost thermostat must be ice cold at that time.
If there is nothing wrong with these two parts, replace the control board.
- The defrost heater Part number: 12729128
- The defrost thermostat Part number: W10165425
- The control board Part number: 12868513
Here are the breakdown diagrams and Parts for Maytag ABB2222FEB2 Refrigerator - AppliancePartsPros.com