38
ICE CEA/CGA1012–1060 Wall Mount AC I&O Manual
03/2021 Rev.1
Dual Unit Phasing
For applications where one controller operates two units, e.g., the CommStat 4 or CommStat Touch
HVAC controller.
Newer HVAC controllers sunch as the CommStat do not require unit phasing. However, if other devices
are connected to the control system, phasing of the air conditioner is required. Earlier models; i.e.,
LL357, LL357A, LL357D2 require the unit to be properly phased.
1. Wire each unit as described in steps 1 through 4 above.
2. Test for proper phasing as follows:
A. Power up the units.
B. Using an AC volt meter set to the 300 volt scale, measure voltage between terminal L1 on
the compressor contactor of unit #1 and terminal L1 on the compressor contactor of unit #2 If
voltage is present, units are wired out of phase and must be rewired.
C. If units are not in phase, turn off power and reverse the field power leads connected to the
internal circuit breaker on one of the units only.
D. Restore power and retest the phase (step B). When the voltage reads "0", the units are in phase.
E. Turn off power and proceed.
Low Voltage Wiring
IMPORTANT.
The following instructions are generic wiring instructions and may not be applicable
for air conditioners with various options. Always refer to the wiring diagram in the air conditioner for
the proper method to wire your unit.
1. On single units, pull the low voltage wiring (e.g., 18 gauge 4-conductor Class 2 thermostat wire)
from the ComPac unit into the thermostat / subbase assembly. See Figure 9b for connections to
various thermostats.
2. Mount the thermostat on the wall of the shelter. The thermostat should be located so that the supply
air from the unit does NOT blow directly on to the thermostat. Connect the thermostat to the terminal
block in the air conditioner as shown in Figures 9a and 9b.
3. On dual units, refer to the
CommStat Touch, CommStat 4 or CommStat 3 HVAC Controller Specification
sheet.
Level and install the controller subbase. Wire the two A/C
units to the Lead/Lag Controller,
according to the wiring diagram on the specification sheet and as shown in Figure 9c or 9d (note:
the diagram also appears on the back cover of the controller).
Remote Signalling:
Terminals 5 & 7(N.O.) and 6 & 7 (N.C.) on the terminal board are dry contacts which
can be used for remote signalling in the event of a/c cutoff on low or high pressure limit.
Continuous fan operation:
For continuous indoor fan operation on single units, install a jumper between
terminals 8 and 3. For continuous indoor fan operation on dual units using the older LL357D4, install
jumper between 8 and 3 and remove jumper between 1 and 3.
CommStat 4 Lead /Lag Controller
Please refer to the Product Data sheet for the Commstat 4 controller for complete instructions
on installing and programming this controller.
CommStat 3 Controller
(See Figure 8d)
The CommStat 3 Controller is a solid state control package designed to operate a fully or
partially redundant air conditioning system for a telecommunication cabinet or shelter. The
CommStat 3 Controller is factory programmed with standard industry set points to facilitate installation.
If desired, each of the set points can be quickly and easily changed in the field by the installer. It can be
used with the ComPac's unique vertical packaged wall mount air conditioners or other environmental
control units. See CommStat 3 Product Data Sheet for installation and programming instructions.
