Johnson Controls System 450 Series - Application 3: Controlling the Temperature of a Walk-In Cooler

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