JOHNSON CONTROLS
197
SECTION 8 – SERVICE
FORM 145.05-NOM7
ISSUE DATE: 10/31/2019
8
Humidity Sensors
The humidity sensor outputs a 0 to 5VDC in response to
the relative humidity sensed. An outdoor air humidity
sensor is used whenever the economizer is configured
for single or dual enthalpy. A return air humidity sensor
is used whenever the economizer is configured for dual
enthalpy. A humidity sensor is also used to monitor the
humidity in the space between the slab and raised floor
system used for FlexSys applications. Table 47 gives
the relationship between the voltage output of the hu-
midity sensor and the % relative humidity.
Digital Thermistor
Compressor (A), the digital unloading compressor has
a discharge thermistor to monitor the discharge pres-
sure. Table 48 shows the temperature to resistance re-
lationship for this thermistor.
TABLE 47 - HUMIDITY SENSOR OUTPUTS
% RELATIVE
HUMIDITY
OUTPUT
VOLTAGE
VDC
% RELATIVE
HUMIDITY
OUTPUT
VOLTAGE
VDC
5 0.25 55 2.75
10 0.50 60 3.00
15 0.75 65 3.25
20 1.00 70 3.50
25 1.25 75 3.75
30 1.50 80 4.00
35 1.75 85 4.25
40 2.00 90 4.50
45 2.25 95 4.75
50 2.50 100 5.00
TABLE 48 - DISCHARGE THERMISTOR TEMPERATURE / RESISTANCE
DEGREE C DEGREE F
RESISTANCE
(KOHMS)
-40.0 -40.0 2889.60
-35.0 -31.0 2087.22
-30.0 -22.0 1522.20
-25.0 -13.0 1121.44
-20.0 -4.0 834.72
-15.0 5.0 627.28
-10.0 14.0 475.74
-5.0 23.0 363.99
0.0 32.0 280.82
5.0 41.0 218.41
10.0 50.0 171.17
15.0 59.0 135.14
20.0 68.0 107.44
25.0 77.0 86.00
30.0 86.0 69.28
35.0 95.0 56.16
40.0 104.0 45.81
45.0 113.0 37.58
50.0 122.0 30.99
55.0 131.0 25.68
60.0 140.0 21.40
65.0 149.0 17.91
70.0 158.0 15.07
DEGREE C DEGREE F
RESISTANCE
(KOHMS)
75.0 167.0 12.73
80.0 176.0 10.79
85.0 185.0 9.20
90.0 194.0 7.87
95.0 203.0 6.77
100.0 212.0 5.85
105.0 221.0 5.09
110.0 230.0 4.45
115.0 239.0 3.87
120.0 248.0 3.35
125.0 257.0 2.92
130.0 266.0 2.58
135.0 275.0 2.28
140.0 284.0 2.02
145.0 293.0 1.80
150.0 302.0 1.59
155.0 311.0 1.39
160.0 320.0 1.25
165.0 329.0 1.12
170.0 338.0 1.01
175.0 347.0 0.92
180.0 356.0 0.83
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