Carrier 69NT40-541-306, Operation And Service

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7–35 T-354
Due to the variations and inaccuracies in ohmmeters, thermometers, or other test equipment, a reading within 2%
of the chart value would indicate a good sensor. If a sensor is defective, the resistance reading will usually be much
higher or lower than the resistance values given.
7.23.2 Sensor Replacement
1. Turn unit power OFF and disconnect power supply.
2. For two wire sensors, cut cable 5cm (2 inches) from shoulder of defective sensor and discard the defective
sensor only. For 3-wire sensors, cut at 23cm (9 inches). Slide the cap and grommet off well mounted sensor
and save for possible reuse.
Do not cut the grommet.
3. If required, prepare the replacement sensor by cut ting sensor wire(s) back 40mm (1-1/2 inch). For 3-wire
sensors, the black wire should be cut at the middle length and the red/white wire cut to the shorter length
(See
Figure 7.29 ).
4. Prepare the cables by cutting wires to the opposite of the sensor (See Figure 7.28 ).
When installing a single wire color two wire sensor, cut one wire of existing two wire cable 40 mm (1-1/2
inch) shorter than the other wire.
When replacing two single sensors with a combination (3-wire) sensor, the black wires of the cables should
be cut to the same length and the red wire of one cable cut to the shorter length.
When replacing a original 3-wire sensor, cut the black wire to the middle length and the red wire to the
shorter length.
Figure 7.28 Sensor and Cable Splice
Table 7–1 Sensor Temperature/Resistance Chart
Temperature (C) Temperature (F) Resistance (Ohms)
RRS, RTS, SRS and STS:
0 32 32,650 +/-91
25 77 10,000 +/-50
AMBS and DTS
0 32
32,650 + 1720
- 1620
25 77
10,000 + 450
- 430
Sensor
Cables
Heat Shrink Tubing
Large Heat Shrink Tubing
REPLACEMENT 2--WIRE TO 2--WIRE OR 3--WIRE TO 3--WIRE
REPLACEMENT FOR DUAL, SINGLE SENSOR CONFIGURATION
RED
BLACK
RED/WHITE
Cable
Sensor