A52x Series Electronic Refrigeration Controller with Adaptive Defrost Technical Bulletin
1
A52x Series Electronic Refrigeration Controller with
Adaptive Defrost
Technical Bulletin
Introduction
This document describes the features and functions of the A52x Electronic Refrigeration Controller with Adaptive
Defrost (A52x Controller), and provides guidelines and instructions to set up, adjust, and troubleshoot the
controller.
Overview
The A52x Controller provides refrigerated space control and defrost control for medium and low-temperature
refrigeration applications. The A525 Controller has five line-voltage relays to control the compressor, defrost
functions, high and low speed evaporator fans, and user-provided alarms. The controller can also control the
following functions:
•
Resistive heat
•
Hot-gas bypass
•
Off-cycle defrost
•
Two-speed evaporator fans
Refer to the
A524/A525 Series Refrigeration Controller with Adaptive Defrost Installation Instructions (Part No. 24-
7664-3310
) for information about relay wiring. The adaptive defrost feature adjusts the defrost schedule to the
minimum number of defrost intervals required to maintain peak efficiency, save energy, and maintain consistent
space temperature.
The A52x Controller has an IP65 enclosure with holes in the enclosure base for wall-surface
mounting. An optional DIN Rail mounting kit (Part No. BKT524-1K) is also available.
IMPORTANT:
Use of this product is subject to and constitutes your agreement to the End User License
Agreement set forth at www.johnsoncontrols.com/buildings/legal/digital LIT No. 12012405.
IMPORTANT:
Use this A52x Refrigeration Controller only as an operating control. Where failure or malfunction
of the A52x Controller could lead to personal injury or property damage to the controlled equipment or other
property, additional precautions must be designed into the control system. Incorporate and maintain other
devices, such as supervisory or alarm systems or safety or limit controls, intended to warn of or protect against
failure or malfunction of the A52x Controller.
IMPORTANT :
Utiliser ce A52x Refrigeration Controller uniquement en tant que dispositif de contrôle de
fonctionnement. Lorsqu'une défaillance ou un dysfonctionnement du A52x Régulateur risque de provoquer des
blessures ou d'endommager l'équipement contrôlé ou un autre équipement, la conception du système de
contrôle doit intégrer des dispositifs de protection supplémentaires. Veiller dans ce cas à intégrer de façon
permanente d'autres dispositifs, tels que des systèmes de supervision ou d'alarme, ou des dispositifs de
sécurité ou de limitation, ayant une fonction d'avertissement ou de protection en cas de défaillance ou de
dysfonctionnement du A52x Régulateur.
LIT No. 12012405
Issued April 2018
