Carrier 19XL - Manual (Page 222)

See Figure 8 for sensor locations. The sensors are immersed directly in the refrigerant or
water circuits. The wiring at each sensor is easily disconnected by unlatching the connector.
These connectors allow only one-way connection to the sensor. When installing a new sensor,
apply a pipe sealant or thread sealant to the sensor threads.
Dual Temperature Sensors
There are 2 sensors each on the bearing and motor temperature sensors for servicing
convenience. In case one of the dual sensors is damaged, the other one can be used by
moving a wire.
The number 2 terminal in the sensor terminal box is the common line. To use the second
sensor, move the wire from the number 1 position to the number 3 position.
Checking Pressure Transducers
There are 3 pressure transducers on the 19XL. These determine cooler, condenser, and oil
pressure. The cooler and condenser transducers also are used by the PIC to determine the
refrigerant temperatures. All 3 can be calibrated if necessary. It is not usually necessary to
calibrate at initial start-up. However, at high altitude locations, calibration of the transducer will
be necessary to ensure the proper refrigerant temperature/pressure relationship. Each
transducer is supplied with 5 vdc power from a power supply. If the power supply fails, a
transducer voltage reference alarm will occur. If the transducer reading is suspected of being