R-23 Refrigeration System Controls, Instruments and Protection Devices

Compressor Discharge Line Temperature Sensor: The controller uses the compressor discharge line temperature sensor to protect the compressor from excessively high operating temperatures. If the discharge gas temperature rises above 148 C (298 F):

• Unit stops immediately; controller activates Alarm LED and records Alarm 56, Compressor Temperature Too High.

• Controller will restart the unit when the sensor temperature is below 138 C (280 F).

High Pressure Cutout (HPCO) Switch: If the compressor discharge pressure rises above 3250 ± 50 kPa, 32.5 ± 0.5 bar, 470 ± 7 psig, the high pressure cutout opens to interrupt the ground circuit to the compressor contactor:

• R-23 compressor STOPS immediately.

• Evaporator and condenser fans and R-134a compressor continue normal operation.

• R-23 compressor will restart when the overload condition is corrected (switch closes) as long as power is available. The high pressure switch resets (closes) when the pressure drops to 2590 ± 250 kPa, 25.9 ± 2.5 bar, 375 ± 38 psig.

Discharge Pressure Gauge: A discharge pressure gauge indicates the refrigerant pressure in the discharge line leaving the compressor.

Receiver Tank Sight Glass: Two sight glasses on the R-23 receiver tank contains three small balls that indicate the level of refrigerant in the tank for checking the refrigerant charge. A moisture indicator in the sight glass changes color to indicate the level of moisture in the system. Check the color of the indicator against the color decal in the sight glass. The dry eye in the sight glass is LIGHT GREEN when the system is dry and YELLOW when the system is wet (contains excessive moisture).

Compressor Oil Sight Glass: A compressor oil sight glass indicates the relative level of compressor oil in the compressor sump.

High Pressure Relief Valve: A high pressure relief valve is installed in the receiver tank. The relief valve protects against excessive pressure build-up within the refrigeration system from extraordinary and unforeseen circumstances. The valve is a spring-loaded piston that lifts when refrigerant pressure exceeds 3447 +520/-104 kPa, 34.47 +5.20/-1.04 bar, 500 +75/-15 psig. The valve is located so that refrigerant pressure expelled from the valve would be directed away from anyone servicing the unit. The valve will reset when this pressure drops to 2758 kPa, 27.58 bar, 400 psig. The valve is non-repairable and requires no adjustment. If the valve fails to reseat properly, recover the refrigerant charge and replace the valve.