Johnson Controls System 450 Series Technical Bulletin

Table 16: C450CCU callouts and descriptions
Callout Description
13 System 450 expansion module two relays: R3 (low speed) and R4 (defrost)
14 System 450 expansion module one relay: R5 (compressor)
15 Power supply path
16 Power return path
Application 2: Controlling the temperature of a walk-in cooler
You can use the C450CCU system to control the temperature of a walk-in cooler using a two-speed
evaporator fan and passive or off-cycle defrost
The following figure shows an off-cycle defrost control system that has the following features:
• Medium temperature with passive defrost
• Space temperature sensor
• Optional System 450 power module
• Optional two-speed evaporator fan motor control
Figure 9: Off‐cycle defrost control system
Table 17: Off‐cycle defrost control system
Callout Description
1 A99 temperature sensor; Sn-1 space temperature sensor
2 Low- voltage input terminal blocks
3 C450CCU condensing unit control module
4 C450YNN power module
5 C450SBN relay expansion module with one relay output
6 OUTR1, 24 VAC to 240 VAC: Controls refrigeration, either compressor or solenoid valve
35System 450 Series C450CCU Condensing Unit Control System Technical Bulletin

Johnson Controls System 450 Series Specifications

General

Brand	Johnson Controls
Model	System 450 Series
Category	Control Unit
Language	English