American Standard UV05 manual Troubleshooting Humidity Sensors, Temperature versus resistance

Diagnostics and Service

3Use the temperature reading from Step 2 to determine the expected sensor resistance from Table 23.

4Using a calibrated ohmmeter, measure the actual resistance across the two sensor leads.

5Compare the expected resistance to the actual resistance.

6If the actual resistance value deviates substantially (more than 10%) from the expected resistance, replace the sensor.

Table 23: Temperature versus resistance

°F (°C)	Resistance in ohms	°F (°C)	Resistance in ohms
–40 (–40)	613	113 (45)	1195
–31 (–35)	640	122 (50)	1237
–22 (–30)	668	131 (55)	1279
–13 (–25)	697	140 (60)	1323
–4 (–20)	727	149 (65)	1368
5 (–15)	758	158 (70)	1413
14 (–10)	789	167 (75)	1459
23 (–5)	822	176 (80)	1506
32 (0)	855	185 (85)	1554
41 (5)	889	194 (90)	1602
50 (10)	924	203 (95)	1652
59 (15)	960	212 (100)	1702
68 (20)	997	221 (105)	1753
77 (25)	1035	230 (110)	1804
86 (30)	1074	239 (115)	1856
95 (35)	1113	248 (120)	1908
104 (40)	1153

Troubleshooting Humidity Sensors

The UVC is configured 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:

1Disconnect the sensors output voltage lead from the UVC analog input.

2Using some other calibrated humidity sensing device, take a humidity reading at the sensor location.

3Use the humidity reading from Step 2 determine the expected sensor voltage from Table 24.

4Using a calibrated multi-meter, measure the actual voltage across the yellow and white sensor leads.

Wire color definitions: White = ground Yellow = output VDC Blue = supply VDC

5Compare the expected voltage to the actual voltage.

6If the actual voltage value deviates substantially (more than 10%) from the expected voltage, replace the sensor.

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