LCD - PENN Controls - A421ABD - A421AED - Electronic Temperature Control - A421 Off‐Cycle Defrost Model

A421 Series Electronic Temperature Controls with Off-Cycle Defrost Installation Guide

PENN Controls
Product name
A421 Off‐Cycle Defrost Model
Document type
Installation Guide
Part number
Document revision
Revision date

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.