Discrete Control - Johnson Controls NXA-FCU-01 Installation Manual

Installation Guide

DISCRETE CONTROL

If the cooling control is discrete, then DO2 and DO3 are used to activate
Stage 1 and Stage 2 of cooling. DO2 must be wired to Cooling Stage 1 and
DO3 must be wired to Cooling Stage 2. Wiring for the Cooling Stage 1 is
shown in Figure 17. To wire DO2 for Cooling Stage1:
1. Connect the HOT terminal to one side of the pilot relay's coil.
2. Connect the DO2 terminal to the other side of the pilot relay's coil.
3. Wire the pilot relay's output to the appropriate specifications for the
device.
J3
Figure 17. DO2 - Cooling Stage 1 Wiring.
24
FCU Controller
HOT DO5 DO4 HOT DO3 DO2 HOT DO1 AO1 AGND
COMPRESSOR
OR
VALVE