Specifications

80
• board for a faulty channel
• a faulty thermistor
For thermistor descriptions, identifiers and connections, see
the Thermistors section.
Alarm 20 — Cooler Heater Feedback Sensor Thermistor
(th.23)
NOTE: Alarm 20 is not used or supported. If this condition is
encountered, confirm machine configuration.
Economizer Gas Thermistor
Alarm 21 — Circuit A (th.24)
Alarm 22 — Circuit B (th.25)
Criteria for Trip — This alarm criterion is tested whether the
unit is ON or OFF. The alarm is tripped if the Economizer gas
reading is outside the range of –40 to 245 F (–40 to 118.3 C).
Action to be Taken — The unit shuts down normally, or is not
allowed to start.
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:
• sensor wiring to the EXV board
• a faulty thermistor
• a faulty channel on the board
See the Thermistors section on page 60 for thermistor descrip-
tion, identifiers and connections.
Discharge Transducer
Alarm 26 — Circuit A (Pr.01)
Alarm 27 — Circuit B (Pr.02)
Criteria for Trip — The criterion is tested whether the circuit is
ON or OFF. This alarm is generated if the voltage as sensed by
the MBB is 0 vdc, which corresponds to the Navigator™ dis-
play of –7 psi (–48.3 kPa).
Action to be Taken — The circuit is shut down normally, or not
allowed to start.
Reset Method — Automatic, once the transducer voltage is
greater than 0 vdc, which corresponds to the Navigator™ dis-
play of a value greater than –7 psi (–48.3 kPa).
Possible Causes — If this condition is encountered, check the
following items:
• sensor wiring to Main Base Board
• board for a faulty channel
• for a faulty transducer
• confirm unit configuration
Suction Pressure Transducer Failure
Alarm 29 — Circuit A (Pr.04)
Alarm 30 — Circuit B (Pr.05)
Criteria for Trip — The criteria are tested whether the circuit is
ON or OFF. The alarm is generated if one of the following
criteria is met:
1. If the voltage as sensed by the MBB is 0 vdc, which
corresponds to the Navigator™ display of –7 psi
(–48.3 kPa).
2. The circuit is ON in cooling mode and the Saturated
Suction Temperature (Saturated Suction Temp, SST)
for the circuit is greater than the Entering Water Tempera-
ture and EXV opening is less than 50% for more than
60 seconds.
Action to be Taken — The circuit is shut down immediately, or
not allowed to start.
Reset Method
1. Automatic, once the transducer voltage is greater than
0 vdc, which corresponds to the Navigator™ display of a
value greater than –7 psi (–48.3 kPa).
2. Automatic once the circuit’s saturated suction tempera-
ture is lower than the Entering Water Temperature by 3° F
(1.6° C). If this criterion trips the alarm 3 times within a
24-hour period, the alarm changes to a manual reset.
Possible Causes — If this condition is encountered, check the
following items:
• sensor wiring to Main Base Board
• board for a faulty channel
• faulty transducer
• faulty entering water temperature sensor
Oil Pressure Transducer
Alarm 34 — Circuit A (Pr.10)
Alarm 35 — Circuit B (Pr.11)
Criteria for Trip — The criteria are tested whether the circuit is
ON or OFF. The alarm is generated if the voltage as sensed by
the CPM board is 0 vdc, which corresponds to the Navigator™
display of –7 psi (–48.3 kPa).
Action to be Taken — The circuit is shut down immediately, or
not allowed to start.
Reset Method — Automatic, once the transducer voltage is
greater than 0 vdc.
Possible Causes — If this condition is encountered, check the
following items:
• sensor wiring to CPM board
• board for a faulty channel
• faulty transducer
• plugged oil filter
• faulty oil solenoid valve coil
• stuck oil solenoid valve
• confirm unit configuration
Economizer Pressure Transducer Failure (sizes 175,200,
250,275,300,350,400 only)
Alarm 37 — Circuit A (Pr. 13)
Alarm 38 — Circuit B (Pr. 14)
Criteria for Trip — The criteria are tested whether the circuit is
ON or OFF. The alarm is generated if the voltage as sensed by
the MBB or Fan Board C is 0 vdc, which corresponds to the
Navigator™ display of –7 psi (–48.3 kPa).
Action to be Taken — The circuit is shut down immediately, or
not allowed to start.
Reset Method — Automatic, once the transducer voltage is
greater than 0 vdc, which corresponds to the Navigator™ dis-
play of a value greater than –7 psi (–48.3 kPa).
Possible Causes — If this condition is encountered, check the
following items:
• sensor wiring to EXV Board
• EXV board for a faulty channel
• faulty transducer
• faulty economizer EXV or EXV wiring
• faulty economizer EXV channel on the board
• closed or partially closed suction service valve
• confirm unit configuration
Loss of Communication with Compressor Board
Alarm 53 — Compressor Board A (Co.A1)
Alarm 54 — Compressor Board B (Co.B1)
Criteria for Trip — The alarm criterion is tested whether the
unit is ON or OFF. If communication with the Compressor
Protection Module Board (CPM) is lost for a period of 10 sec-
onds, the alarm will be generated.
Action to be Taken — The affected compressor will be shut
down.
Reset Method — Automatic, if communication is established.
If called for, the compressor will start normally.
Possible Causes — If this condition is encountered, check the
following items:
• power supply to the affected CPM board