Page 77
XP25
SENSOR
RESISTANCE VALUES
RANGE (OHMS)
TEMP RANGE ºF
(ºC)
PIN# / WIRE
SLEEVE COLOR
LIQUID LINE
OUTDOOR
AMBIENT
COIL
4 AND 3
(BLACK)
6 AND 5
(BROWN)
2 AND 1
(YELLOW)
-40 (-40) TO
140 (60)
336,000 to 2,487 (see
table 18 on page 78 for
exact temperature to
ohm readings)
COIL
OUTDOOR
AMBIENT
LIQUID LINE
TEMPERATURE
SENSOR HARNESS
BLACK WIRES WITH
BROWN SLEEVE
BLACK WIRES WITH
BLACK SLEEVE
BLACK WIRES WITH
YELLOW SLEEVE
Figure 58. Temperature Sensor Specifications
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.
OUTDOOR AMBIENT
TEMPERATURE
SENSOR
(-060) COIL TEMPERATURE
SENSOR (RT21) - ON
RETURN BEND, 12 TUBES
UP FROM BOTTOM (11.50'
UP)
(-048) COIL TEMPERATURE
SENSOR (RT21) - ON
RETURN BEND, 16 TUBES
UP FROM BOTTOM (15.50'
UP)
LIQUID LINE SENSOR
(-024 AND -036) COIL
TEMPERATURE SENSOR
(RT21) - ON RETURN BEND,
12 TUBES UP FROM
BOTTOM (11.50' UP)
CRANKCASE HEATER
THERMOSTAT (S40) OPENS AT
70ºF, CLOSES AT 50ºF
Figure 59. Temperature Sensor Locations
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