122
Temperature Sensor
Intake (SN-01)/Return (SN-02)/Outdoor (SN-03)/Discharge (SN-04)/Space (HUM-2)
Refer to
component locations. Check the following:
1. Make sure the unit is OFF.
2. Make sure the wires are connected properly.
3. Measure the resistance of the temperature sensor. Use the temperature/ohm chart to determine your
readings.
• SN-01 – J15 pin 1 to pin 2
• SN-02 – J15 pin 3 to pin 4
• SN-03 – J15 pin 5 to pin 6
• SN-04 – J15 pin 7 to pin 8
• HUM-2 – J15 pin 9 to pin 10
- If there is
0 ohms
,
the sensor or wires are shorted.
- If there is
infinite (OL) ohms
,
the sensor or wires are open.
If the sensor or wiring has failed, replace the sensor.
NOTE: SN-03 is located behind the damper assembly.
Figure 56 - Temperature Sensors
SN-03
SN-02
SN-01
SN-04
Temperature
Ohm 10k
-20
-10
0
10
20
30
40
50
60
70
80
90
100
165k
117k
85k
62k
46k
34k
26k
19k
11k
9k
7k
5k
15k
10
1
J15
THERMIST
ORS
HUM-2
+
-
SPACE
RD
BK
INTAKE
SN-01
RD
GR
BK
RD
BK
RD
BK
RD
DISCHARGE
OUTDOOR
RETURN
SN-04
RD
BK
SN-03
RD
BK
SN-02
RD
BK