Technical Guide

505428-YTG-M-0512
Johnson Controls Unitary Products 127
Typical Field Wiring Diagram - Twin NC090 Evaporator Units with 4-Pipe Condenser Unit
NOTE: On non NC/ND Evaporator models, isolation relays
must be installed to avoid overloading on 75 VA
transformers on the condensing unit.
R C
Y1
G W1 R C
Y1
G W1
THERMOSTAT
SINGLE STAGE COOLING
TWO STAGE HEATING
W2 W2
THERMOSTAT
SINGLE STAGE COOLING
TWO STAGE HEATING
X X