Instruction manual
OM 751-4 44 www.DaikinApplied.com
dIaGnostICs and serVICe
Troubleshooting Humidity Sensors
The UVC is congured to use a 0–100% RH, 0–5 VDC, capacitive humidity sensor.
Each sensor is calibrated according to the table shown.
CAUTION
The humidity sensor is not protected against reversed polarity. Check carefully when connecting the
device or damage can result.
Use the following procedure to troubleshoot a suspect sensor:
1. Disconnect the sensors output voltage lead from the UVC analog input.
2. Using some other calibrated humidity sensing device, take a humidity reading at the
sensor location.
3. Use the humidity reading from Step 2 determine the expected sensor voltage from
Table 24 on page 44.
4. Using a calibrated multi-meter, measure the actual voltage across the yellow and
white sensor leads.
Wire color denitions:
White = ground
Yellow = output VDC
Blue = supply VDC
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.
Table 24: Humidity versus voltage
RH (%) VDC (mV) RH (%) VDC (mV)
10 1330 55 2480
15 1475 60 2600
20 1610 65 2730
25 1740 70 2860
30 1870 75 2980
35 1995 80 3115
40 2120 85 3250
45 2235 90 3390
50 2360 95 3530