68-0173—3 24
CAUTION
Disconnect power supply before connecting the
wiring to prevent electrical shock or equipment
damage.
Wiring must comply with applicable codes, ordinances and
regulations.
1. Wire the C7089A Outdoor Sensor to the terminals
marked OUT on the W8900A-C Remote Module. If the
leadwire provided with the C7089A is not long enough,
run cable to a hole at the selected C7089A location.
Color-coded, 18-gauge thermostat wire is recom-
mended. Refer to Fig. 28 for an example of general wir-
ing for the C7089A. Pigtail wiring can be used.
2. Mount the C7089A in its mounting clip.
3. Plug wiring hole using nonhardening caulk or putty.

Mounting the C7100A Discharge Air Sensor

(if needed)
Location Guidelines
• Locate the C7100A Discharge Air Sensor in the air duct or
plenum where it can sample an average air temperature.
• Avoid locations where air stratification can cause sensor
errors.
• The distance between the C7100A and W8900A-C should
not exceed 200 ft.
Mounting
TO MOUNT ON A FLAT DUCT OR PLENUM SURFACE:
1. Cut a 7/8 in. (22 mm) hole in the duct or plenum surface
at the desired location.
2. Insert the sensor probe into the duct or plenum with inlet
holes facing the air stream.
3. If necessary, use the flange provided as a template to
mark and drill four holes for 8-32 mounting screws.
4. Fasten the sensor to the duct or plenum surface with
the four 8-32 sheetmetal screws provided.
TO MOUNT IN A 2 X 4 IN. JUNCTION BOX:
1. Cut a 7/8 in. (22 mm) hole in the duct or plenum surface
at the desired location.
2. Remove the center rear knockout from the 2 x 4 in. junc-
tion box and insert the sensing probe through the
knockout with the flange flat against the junction box.
3. Using the flange (provided) as a template, mark and drill
four holes in the junction box and the duct or plenum
surface for 8-32 mounting screws.
4. Insert sensor probe through both the junction box
knockout and the 7/8 in. (22 mm) hole drilled in the duct
or plenum and fasten the junction box and sensor to the
duct or plenum surface.

Wiring the C7100A Discharge Air Sensor

(if needed)
CAUTION
Failure to use the following wiring practices can
introduce electrical interference (noise), which can
cause erratic system operation.
Keep wiring at least one foot away from large inductive
loads such as motors, line starters, lightning ballasts,
and large power distribution panels. Use shielded
cable to reduce interference when rerouting wires is
not possible. Ground the shielded cable to the ground
terminal on the W8900A-C.
IMPORTANT
Erratic temperature readings from a sensor can
occur as a result of any of the wiring practices
described below. Use shielded cable to reduce inter-
ference if rerouting sensor wiring is not possible.
These practices must be avoided to assure proper
operation:
— Do not route temperature sensor wiring with building
power wiring, next to control contactors or near light
dimming circuits, electric motors or welding equip-
ment.
— Avoid poor wiring connections.
— Avoid intermittent or missing building earth ground.
— If the discharge air temperature fails to display when
the check key is pressed, see the Troubleshooting
Section.
CAUTION
Disconnect power supply before connecting the
wiring to prevent electrical shock or equipment
damage.
Wiring must comply with applicable codes, ordinances and
regulations.
Wire the C7100A Discharge Air Sensor to the terminals
marked T and T1 on the W8900A-C Remote Module. Use 1/4
in. female quick connects on the C7100A.
INSTALLER SETUP
IMPORTANT
Installer setup must be done for the HVAC equip-
ment and the PC8900A/W8900A-C to operate
properly.
The installer setup mode is used by the installer to configure
the PC8900A/W8900A-C for the HVAC equipment used at the
installation (heating, cooling, ventilation, humidification, air
cleaning) and to configure the PC8900A operation
(changeover mode, remote sensors, and outdoor sensors).