Heatcraft Refrigeration Products 25001501 Installation & Operating Instructions Manual page 21

SERVICE DIAGNOSIS CHART - GENERAL
PROBLEM
Low suction pressure
Loss of oil or loss of oil
pressure
Freezer coil icing
BEACON CONTROLLER
POSSIBLE CAUSE
1. Insufficient refrigerant
2. Freezer coil iced up
3. Plugged liquid line filter drier
4. Plugged suction filter
5. Expansion valve starving coil
1. Insufficient oil in the system
2. Compressor short cycling
3. Excessive liquid refrigerant in
compressor crankcase
4. Worn bearings
1. Insufficient refrigerant
2. Wrong defrost end temp setting
3. Wrong defrost fail-safe setting
4. Not enough defrost for application
5. Coil not feeding properly
6. System undersized
POSSIBLE CORRECTIVE ACTION
1. Check system for leaks; repair leaks &
add refrigerant
2. Check defrost system operation &
correct fault condition
3. Replace filter drier
4. Replace suction filter
5. Check expansion valve superheat setting on
control board; check expansion valve screen
1. Add oil until sight-glass is 1/2 full
2. Check low pressure control settings
3. Check crankcase heater; check expansion valve
superheat setting on control board; check for
internal rupture of heat exchanger
4. Replace compressor
1. Check system for leaks; repair leaks &
add refrigerant.
2. Check unit cooler instructions. Raise setting.
3. Check unit cooler instructions. Raise setting.
4. Check for subcooled liquid, incorrect nozzle
selection, insulate liquid line, restricted coil
5. Do heat load & check sizing
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