Temperature Sensor Specifications; Temperature Sensor Locations - Lennox XP25-024-230-01 Installation And Service Procedure

COIL
OUTDOOR
AMBIENT
LIQUID LINE
CHECKOUT
Sensors connect to the outdoor control through a field‐replaceable harness assembly that plugs into the control. Through the
sensors, the control detects outdoor ambient, coil and liquid temperature fault conditions. As the detected temperature
changes, the resistance across the sensor changes. Table 18 on page 78 shows how the resistance varies as the temperature
changes for both type of sensors. Check sensor operation by reading ohms across pins shown in figure 58.
NOTE - When checking the ohms across a sensor, be aware that a sensor showing a resistance value that is not within the
range shown in table 18 on page 78, may be performing as designed. However, if a shorted or open circuit is detected, then the
sensor may be faulty and the sensor harness will need to be replaced.
CRANKCASE HEATER
THERMOSTAT (S40) OPENS AT
70ºF, CLOSES AT 50ºF
TEMP RANGE ºF
SENSOR
(ºC)
COIL
-40 (-40) TO
OUTDOOR
140 (60)
AMBIENT
LIQUID LINE
BLACK WIRES WITH
BROWN SLEEVE
BLACK WIRES WITH
BLACK SLEEVE
BLACK WIRES WITH
YELLOW SLEEVE
Figure 58. Temperature Sensor Specifications
(-024 AND -036) COIL
TEMPERATURE SENSOR
(RT21) - ON RETURN BEND,
12 TUBES UP FROM
BOTTOM (11.50' UP)
OUTDOOR AMBIENT
TEMPERATURE
SENSOR
Figure 59. Temperature Sensor Locations
RESISTANCE VALUES
SLEEVE COLOR
RANGE (OHMS)
336,000 to 2,487 (see
table 18 on page 78 for
exact temperature to
ohm readings)
LIQUID LINE SENSOR
Page 77
PIN# / WIRE
6 AND 5
(BROWN)
4 AND 3
(BLACK)
2 AND 1
(YELLOW)
TEMPERATURE
SENSOR HARNESS
(-048) COIL TEMPERATURE
SENSOR (RT21) - ON
RETURN BEND, 16 TUBES
UP FROM BOTTOM (15.50'
UP)
(-060) COIL TEMPERATURE
SENSOR (RT21) - ON
RETURN BEND, 12 TUBES
UP FROM BOTTOM (11.50'
UP)
XP25