Johnson Controls System 450 Series Technical Bulletin

Table 17: Off‐cycle defrost control system
Callout Description
7 OUTR2, 24 VAC to 240 VAC : High-speed evaporator fan control circuit
8
120 VAC or 240 VAC supply power terminals: provide 120 VAC or 240 VAC supply power to optional C450YNN
power module.
9 Optional: OUTR3, 24 VAC to 240 VAC: Low-speed evaporator fan control circuit
The following menu flow shows the defrost control UI menu flow. The dash-outlined screens are
optional setup screens.
Figure 10: Off-cycle defrost control UI menu flow
Application 3: Controlling the temperature of a walk-in cooler
You can use the C450CCU system to control the temperature of a walk-in cooler using one or two-
speed evaporator fans and electric defrost
The following figure shows an active electric heat defrost control system that has the following
features:
• Low or medium temperature with electric defrost
• Space temperature sensor
• Evaporator temperature sensor or switch for defrost termination
• Optional System 450 power module
• Single or optional two speed evaporator fan motor control
System 450 Series C450CCU Condensing Unit Control System Technical Bulletin36

Johnson Controls System 450 Series Specifications

General

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