Direct-mounting a Type 1/IP20 control to a wall or other flat surface using the four keyhole slots - PENN Controls - A421ABD - A421AED - Electronic Temperature Control - A421 Off‐Cycle Defrost Model

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

Product name
A421 Off‐Cycle Defrost Model
Document type
Installation Guide
Document revision
Revision date


  1. Disconnect the power and remove the enclosure cover. Place the control horizontally against the wall surface in a suitable location, and mark the keyhole slot locations on the mounting surface.
  2. Install appropriate screws or fasteners and leave the screw heads approximately one or two turns away from flush to the mounting surface.
  3. Position the control mounting slots over the screw heads, and then tighten the mounting screws to secure the control to the surface.
    Note: When you mount the control on an uneven surface, use shims to mount the control evenly.