Sensors; Thermistors - Carrier AQUASNAP 30RB060-390 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

outside the range of –40 F (–40 C) to 240 F (115.6 C). This
alarm is for units with the heat reclaim option only.
Action to be Taken — None
Reset Method — Automatic, the alarm will reset once the
thermistor reading is within the expected range.
Possible Causes — If this condition is encountered, check the
following items:
• Check the sensor wiring to the heat reclaim board.
• Check for a faulty thermistor.
• Check the board for a faulty channel.
• Confirm unit configuration.
th.10 — OAT Thermistor Failure
Criteria for Trip — If the outdoor air temperature as measured
by the thermistor is outside of the range –40 F (–40 C) to 240 F
(115.6 C).
Action to be Taken — Unit shuts down under normal condi-
tions or is not allowed to start. Temperature reset based on
outdoor air temperature will be disabled.
The OAT sensor controls the cooler heaters. If this sensor
fails, the cooler heaters will be energized when the machine
stages to 0.
Reset Method — Automatic, the alarm will reset once the
thermistor reading is within the expected range and Tempera-
ture reset based on outdoor-air temperature will be enabled.
Possible Causes — If this condition is encountered, check the
following items:
• Check the sensor wiring to the main base board.
• Check for a faulty thermistor.
For thermistor descriptions, identifiers and connections, see
Thermistors on this page.
th.11 — Master/Slave Common Fluid Thermistor
Criteria for Trip — This alarm criterion is checked whether the
unit is ON or OFF and has been configured for Dual Chiller
Control. The alarm will be triggered if the Dual Chiller
Common Fluid temperature as measured by the thermistor is
outside of the range –40 F (–40 C) to 240 F (115.6 C).
Action to be Taken — Dual Chiller Control disabled. Units
operate as a stand-alone machine.
Reset Method — Automatic, once the thermistor reading is
within the expected range. The Dual Chiller algorithm will
resume once the alarm is cleared.
Possible Causes — If this condition is encountered, check the
following items:
• Check the sensor wiring to the main base board.
• Check for a faulty thermistor.
For thermistor descriptions, identifiers and connections, see
Thermistors on this page.
Suction Gas Thermistor
th.12 — Circuit A
th.13 — Circuit B
th.14 — Circuit C
Criteria for Trip — This alarm criterion is checked whether the
unit is ON or OFF. If the suction gas temperature as measured
by the thermistor is outside of the range –40 F (–40 C) to 240 F
(115.6 C), the alarm will be triggered.
Action to be Taken — The affected circuit shuts down
normally.
Reset Method — Automatic, once the thermistor reading is
within the expected range. The affected circuit will restart once
the alarm has cleared.
Possible Causes — If this condition is encountered, check the
following items:
• Check the sensor wiring to the EXV board.
• Check the board for a faulty channel.
• Check for a faulty thermistor.
For thermistor descriptions, identifiers and connections, see
Thermistors on this page.
Condenser Subcooling Liquid Thermistor
th.18 — Circuit A
th.19 — Circuit B
Criteria for Trip — Tested when the unit is On or Off. If the
temperature as measured by the sensor is outside of the range
of –40 F (–40 C) to 240 F (115.6 C). This alarm is for units
with the heat reclaim option only.
Action to be Taken — The unit will return to the air cooled
mode.
Reset Method — Automatic, the alarm will reset once the read-
ing is within the expected range.
Possible Causes — If this condition is encountered, check the
following items:
• Check the sensor wiring to the EMM HR.
• Check for a faulty thermistor.
• Confirm unit configuration.
th.21 — Space Temperature Sensor Failure
Criteria for Trip — This alarm criterion is checked whether the
unit is ON or OFF and if Space Temperature Reset has been
enabled. If the outdoor-air temperature as measured by the
thermistor is outside of the range –40 F (–40 C) to 240 F
(115.6 C), the alarm will be triggered.
Action to be Taken — Unit operates under normal control.
Temperature Reset based on Space Temperature is disabled.
Reset Method — Automatic, once the thermistor reading is
within the expected range. The Space Temperature Reset will
resume once the alarm has cleared.
Possible Causes — If this condition is encountered, check the
following items:
• Check the sensor wiring to the energy management
module.
• Check the board for a faulty channel.
• Check for a faulty thermistor.
For thermistor descriptions, identifiers and connections, see
Thermistors below.
The electronic control uses up to six thermis-
Sensors —
tors to sense temperatures and up to six transducers to sense
pressure for controlling chiller operation. These sensors are
outlined below.
Thermistors (Tables 45-46B) —
monitoring the chiller's operation include: cooler entering wa-
ter, cooler leaving water, dual chiller leaving water, compressor
suction gas temperature, and outside air thermistors. These
thermistors are 5 kat 77 F (25 C) and are identical in temper-
ature versus resistance. The space temperature thermistor is
10 k at 77 F (25 C) and has a different temperature vs.
resistance.
COOLER LEAVING FLUID SENSOR — On all sizes, this
thermistor is installed in a friction fit well in the leaving water
nozzle of the cooler. See Fig. 34 and 35.
COOLER ENTERING FLUID SENSOR — On all sizes,
this thermistor is factory-installed in a friction fit well in the
entering water nozzle of the cooler.
DUAL CHILLER LWT — On duplex chillers, 30RB315-
390, a factory-supplied, field-installed friction fit well and
thermistor are installed in the common supply water header of
the two modules.
COMPRESSOR RETURN GAS TEMPERATURE — This
thermistor is factory-installed in a friction fit well located in the
common suction line for the circuit. There is one thermistor for
each circuit.
71
Thermistors that are