Flooded type water cooled screw chiller (PCB Control) MCAC-CTSM-2012-11
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Change filter drier at the first sign of moisture in the system.
IMPORTANT: Unit must in operation for at least 12 hours before moisture indicator can give an accurate
reading. With the unit running, the indicating element must be in contact with liquid refrigerant to give
true reading.
Liquid Line Service Valve
This valve is located ahead of the filter drier and provides a 1/4-in. Schrader connection (30GXN,R only)
for field charging. In combination with compressor discharge service valve, each circuit can be pumped
down into the high side for servicing.
Thermistors
For PTC thermistors, resistances vary with various temperatures.
Location
Motor thermistor locates in the motor winding and is connected to the compressor protection module
which will cut off the main power when motor winding temperature exceeds 110 °C. Water temperature
thermistors are installed in wells on chilled water inlet/outlet and cooling water inlet/outlet. Refer to the
electric control wiring diagram for detail connection information.
Thermistor replacement
To Replace Thermistors RT1, RT2, RT3, RT4, RT5, or RT6 (Entering/Leaving chilled Water;
Entering/Leaving cooling Water; Discharge Gas Temperature) — Disconnect appropriate connector from
the PCB controller. New thermistors should be spliced to existing wiring close to the connector unless
new connectors are required. Remove thermistor cable from harness. Remove and discard original
thermistor from well. Insert new thermistor in well body to its full depth. Add a small amount of thermal
conductive grease to thermistor probe and well. Tighten the screw to prevent thermistors from slipping
out of the well.
To Service Compressor Motor Thermistors
A thermistor is factory installed in each compressor. Connections for the thermistors are located in the
compressor wiring box. 2 terminals are reserved for the thermistor: S1 and S2. Motor temperature is
measured by leads connected to S1 and S2 terminal. The thermistors are not serviceable in the field. If
the compressor motor thermistor fails, compressor replacement is required.
Safety Devices
Compressor protection module (INT69 HBY/ JTX-A)
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