5
Fig. 11 — CO
2
Bracket for 48/50P055-100 and
48/50Z055-105 Units
(No Economizer or Power Exhaust)
48/50N Units
The CO
2
sensor is to be installed in the predrilled holes located
in the power exhaust section. See Fig. 12.
1. Shut off unit power supply.
2. Open the power exhaust section doors to gain access.
3. Remove the sensor and cover from the sensor mounting
plate.
4. Secure mounting plate to the bracket with no. 8 screws.
5. The electrical wire harness for the CO
2
sensor is factory
installed. Locate the four wires in the power exhaust section.
Wire the electrical harness to the sensor as shown in Fig. 4.
6. Attach the sensor to the mounting plate. Figure 12
includes power exhaust. Mounting location is the same for
units with return fan and no power exhaust.
Fig. 12 — 48/50N CO
2
Sensor Mounting Location
START-UP
After applying power, the CO
2
sensor will enter a warm-up
mode. Warm-up duration will be from 1 to 10 minutes. The
warm-up duration will be shorter in warmer temperatures and
longer in cooler temperatures. During warm-up, the signal out-
put will be 4 mA. Once the unit has warmed up, the voltage or
current output will be set up to indicate the CO
2
level. The dis-
play will show a steady reading 1 minute later.
Configuring the
Comfort
Link
Controller
The CO
2
sensor is defaulted to provide 4 mA at 0 ppm and 20 mA
at 2000 ppm. If a different range is necessary, contact Carrier Ap-
plication Engineering to reconfigure the sensor. If the sensor is re-
configured, the mA range on the
Comfort
Link controller must be
configured to match the new values
.
Refer to Controls and Trou-
bleshooting Guide for configuration details.
Sensor Self-Calibration
The CO
2
sensors employ a self-calibration system. The system
eliminates the need for manual calibration in applications
where the indoor CO
2
level drops to outside levels during un-
occupied periods (e.g., during evening hours). A special soft-
ware routine in the sensor remembers the background readings
for 14 consecutive evenings, calculates if there is a sensor drift,
and then corrects for it.
NOTE: This only applies when used in typical indoor or ambient
air conditions. Consult Carrier application engineering if other
gases or corrosive agents are part of the application environment.
SERVICE
Cleaning
The controller is a rugged and lightweight unit that requires
very little maintenance. Clean external surfaces periodically
with a dampened cloth.
TROUBLESHOOTING
The following occurrences may indicate abnormal operation,
caused primarily by power input fluctuations, surges, or spikes.
• The unit remains in warm-up mode for more than 10 minutes.
• The LED glows with no pulse.
• CO
2
indication (display numbers or signal output) is frozen.
• Numbers on the display change continuously for longer
than 1 minute.
Normal operation can usually be restored by removing power,
shutting down the unit for at least 15 seconds, then reconnect-
ing power. The unit should warm up, as described above, then
return to normal operation. If the situation continues, remove
and replace the sensor.
CO2
S
EN
S
OR
AND BRACKET
BRACKET
CO
2
SENSOR
