Instruction manual

www.DaikinApplied.com 45 OM 751-4
dIaGnostICs and serVICe
Troubleshooting Carbon Dioxide (CO
2
) Sensors
The UVC is congured to use a 0–2000 PPM, 0–10 VDC, single beam absorption infra-
red gas sensor. Each sensor is calibrated according to the table shown.
Use the following procedure to troubleshoot a suspect sensor.
1. Disconnect the sensors output voltage lead from the UVC analog input (xAI-3).
2. Using some other calibrated CO
2
sensing device, take a CO
2
reading at the sensor
location.
3. Use the CO
2
reading from Step 2 to determine the expected sensor voltage from
Table 25.
4. Using a calibrated multi-meter, measure the actual voltage across the lead removed
from xAI-3 and ground.
5. Compare the expected voltage to the actual voltage.
6. If the actual voltage value deviates substantially (more than 10%) from the expected
voltage, replace the sensor.
In the unlikely event that the CO
2
sensor requires calibration, consult the factory for
information on obtaining calibration equipment and instructions.
Table 25: CO
2
versus voltage table
CO
2
(PPM) VDC (V) CO
2
(PPM) VDC (V)
300 1.5 1200 6.0
400 2.0 1300 6.5
500 2.5 1400 7.0
600 3.0 1500 7.5
700 3.5 1600 8.0
800 4.0 1700 8.5
900 4.5 1800 9.0
1000 5.0 1900 9.5