The A421 Series Control has a backlit LCD screen (Figure 1). You can adjust the LCD brightness. During normal operation, the LCD displays the Main screen, which provides the following information:
- Temperature sensed at the A99 sensor
- Selected temperature units (°F or °C)
- Mode of operation (Flame = Heating mode, Snowflake = Cooling mode)
- Binary Input status (BIN) when a user-supplied momentary switch is connected and closed to manually start or stop a defrost cycle.
During setup and adjustment, the LCD displays the parameter code screens and the parameter value screens. See the A421 Control parameter setup menus for more information.