JOHNSON CONTROLS
34
FORM 150.73-NM1
ISSUE DATE: 07/03/2024
SECTION 4: INSTALLATION
The removable conduit entry plates, lo-
cated on the bottom of the power panel
enclosure, must be removed from the
enclosure prior to using tools to cut out
the appropriate size knockouts for con-
duit entry. There are also predetermined
knockout holes located in the control sec-
tion of the power panel.
Do not make any penetrations into the en-
closure, except through the conduit entry
plates when they are removed from the
enclosure. Failure to remove the conduit
entry plates prior to cutting appropriately
sized knockouts can result in an arc ash
event which can cause damage to the
equipment or injury to personnel.
Use a tool that is designed to cut large
diameter wire to cut the incoming power
and ground wiring to length outside of the
enclosure. Do not use a grinder, recipro-
cating saw, or any similar tool to cut wires
to length. Failure to use the appropriate
tool to cut wiring can result in an arc
ash event which can cause damage to the
equipment or injury to personnel.
Liquid line solenoid connections
The field supplied and installed liquid line solenoid
valves should be installed at the evaporator and wired
using 18 AWG minimum wire. Electrical connections
should be made at 1-XTBF for Sys. #1 and 2-XTBF for
Sys. #2. Note that power for the solenoid coil is 120
VA C . See Figure 11 on page 68, Figure 12 on page
78, and unit wiring diagram.
Discharge air sensor
The discharge air sensor and associated connector
hardware is factory supplied but must be field installed.
Field wire must be field supplied (QUABBIN 930421-
2 or equivalent 2 conductor with shield and drain wire
- 20 AWG 300 V 60°C - polyethylene insulation UV
resistant). Field wiring is connected to pins 3, 6, and
9 of J6 on the microboard. See Figure 9 on page 40
and unit wiring diagram.
Zone thermostats for remote start and stop
Field-supplied thermostats or dry contacts must be
field-wired when operating the unit in Suction Pres-
sure Control Mode. The System 1 zone thermostat is
field wired at XTBC1 terminals 13 to 51. On two sys-
tem units, System 2 zone thermostat is field wired to
XTBC1 terminals 13 to 50. XTBC 1 terminal is located
near the bottom of the micro control panel. See Figure
3 on page 21 and unit wiring diagram.
See Air Proving Switch/Remote Start-Stop
Contacts.
Air proving switch/remote start-stop contacts
The Air Flow Switch MUST NOT be used
to start and stop the chiller (i.e. starting
and stopping the chilled water pump). It
is intended only as a safety switch.
The air proving switch is field wired to XTBC1 termi-
nals 13 to 50 (SYS 1) and 13 to 51 (SYS 2) to prevent
operation of the refrigerant circuit when the supply air
blower is not operating.
If separate evaporator blowers are used with respect
to each refrigerant system in the condensing unit, then
two air proving must be wired in series across XTBC1
terminals 13 - 50 and 13 - 51 (one for each evaporator
blower). See Figure 10 on page 41 and unit wiring
diagram.
When using Zone Thermostats in Suction Pressure con-
trol mode, the air proving switch(s) should be wired in
series with the respective Zone Thermostats.
Remote start/stop contacts
To remotely start and stop the condensing unit, dry
contacts can be wired in series with the air proving
switch and XTBC1 - terminals 13 to 50 (SYS 1) and
13 to 51 (SYS 2). See Figure 10 on page 41 and unit
wiring diagram.
Remote emergency cutoff
Immediate shutdown of the condensing unit can be
accomplished by opening a field installed dry contact
to break the electrical circuit between terminals 5 to L
on terminal block XTBC2. XTBC2 is located in the
power panel. The unit is shipped with a factory jumper
installed between terminals 5 to L, which must be re-
moved if emergency shutdown contacts are installed.
See Figure 10 on page 41 and unit wiring diagram.
Evaporator blower start contacts
For constant fan operation: Terminal block XTBC2 -
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