Carrier 40UV - Sensors

29
Sensors
ROOM-AIR TEMPERATURE (RAT) SENSOR — The RAT
sensor is factory-installed and factory-wired to the control. It
measures the temperature of the air returning to the unit from
the space.
The sensor consists of a thermistor, encased within an
epoxy bead. See Fig. 12. It is mounted behind the front center
panel, where it is hidden from view.
The sensor has a range of –40 to 245 F with a nominal
resistance of 10,000 ohms at 77 F. The sensor is connected to
terminals T1 and T2 on the controller board. See Table 11.
Polarity is not a consideration. See Table 10 for resistance vs
temperature values.
SUPPLY-AIR TEMPERATURE (SAT) SENSOR — The SAT
is factory-installed and factory-wired to the control module. It
measures the temperature of the air leaving the unit.
The sensor consists of a thermistor encased within an epoxy
bead. It is mounted in the fan discharge with the probe mount-
ed to sense the air temperature supplied to the room. See
Fig. 12.
The sensor’s thermistor has a range of –40 to 245 F with a
nominal resistance of 10,000 ohms at 77 F.
NOTE: A temperature of the supply air includes fan heat.
In the control box, the sensor wires are connected to termi-
nals T3 and T4 (SAT) on the controller board (see Table 11).
Polarity is not a consideration. See Table 12 for resistance vs
temperature values.
Table 11 — Sensor Connections
Table 12 — Thermistor Resistance vs Temperature Values for Room-Air Temperature Sensor,
Supply-Air Temperature Sensor, Mixed-Air Temperature Sensor,
and Optional Space Temperature Sensor
SENSOR
CONTROL
MODULE
PIN NO.
Unit Mounted Room-Air Temperature
Sensor (RAT)
T1 and T2
Space Temperature Sensor (SPT) Wall
Mount (Option)
T1, T9, T10, Shield
Supply-Air Temperature (SAT) T3 and T4
Mixed-Air Temperature Sensor (MAT) T5 and T6
Outdoor-Air Temperature Sensor (OAT) T7 and T8
TEMP
(C)
TEMP
(F)
RESISTANCE
(Ohms)
–40 –40 335,651
–35 –31 242,195
–30 –22 176,683
–25 –13 130,243
–20 –4 96,974
–15 5 72,895
–10 14 55,298
–5 23 42,315
03232,651
54125,395
10 50 19,903
15 59 15,714
20 68 12,494
25 77 10,000
30 86 8,056
35 95 6,530
40 104 5,325
45 113 4,367
50 122 3,601
55 131 2,985
60 140 2,487
65 149 2,082
70 158 1,752
Fig. 12 — Room-Air Temperature and Supply-Air
Temperature Sensor (Part No. HN79NZ005)