Refrigeration Diagnostics
| Condition | Possible Cause | Remedy |
|---|---|---|
| Load temperature too high - unit not cooling. | Compressor does not operate. | Refer to (Mechanical Diagnostics). |
| Controller setpoint too high. | Adjust controller setpoint. | |
| Defective container insulation or poor fitting doors. | Repair container. | |
| Shortage of refrigerant. | Repair leak and recharge. | |
| Overcharge of refrigerant. | Purge system. | |
| Air in refrigeration system. | Evacuate and recharge. | |
| Vapor injection valve open. | Check vapor injection valve circuit and compressor discharge temperature sensor. | |
| Too much compressor oil in system. | Remove compressor oil from compressor. | |
| Iced or dirty evaporator coil. | Defrost or clean evaporator coil. | |
| Restricted lines on high side. | Clear restriction. | |
| Plugged filter drier/in-line filter. | Change filter drier. | |
| Compressor Digital Control Valve defective. | Replace defective valve. | |
| Condenser coil dirty or airflow restricted. | Clean condenser coil, clear restriction, or repair or replace fan motor or condenser fan blade. | |
| No water flow to water-cooled condenser. | Restore water flow to water-cooled condenser-receiver tank. | |
| Defective water pressure switch (Option). | Replace switch. | |
| Expansion valve open too much. | Adjust or replace valve. | |
| Expansion valve power element lost its charge. | Replace power element. | |
| Expansion valve feeler bulb improperly mounted, poorly insulated or making poor contact. | Correct feeler bulb installation. | |
| Head pressure too low.
注意 This
unit has a digital capacity control system. Suction and discharge
pressures may drop below expected normal readings when the unit is
in Modulation Cool (control temperature within 10 C (18 F) of setpoint
or in Power Limit mode).
|
Shortage of refrigerant. | Repair leak and recharge. |
| Low ambient air temperature. | No remedy. | |
| Service gauge out of calibration. | Replace gauge. | |
| Head pressure too high. | Refrigerant overcharge. | Purge system. |
| Air in refrigeration system. | Evacuate and recharge. | |
| Dirty or restricted condenser coil. | Clean condenser coil. | |
| Condenser fan not operating. | Refer to “Condenser Fan Motor Does Not Operate” (Mechanical Diagnostics). | |
| Condenser fan grille damaged or missing. | Repair or replace grille. | |
| Condenser fan blade damaged. | Replace fan blade. | |
| High ambient air temperature. | No remedy. | |
| Restricted dehydrator or high side. | Replace filter drier or clear restriction. | |
| Defective service gauge. | Replace gauge. | |
| Compressor loses oil. | Refrigerant leak. | Repair leak and recharge. |
| Compressor oil migrates to system. | Short cycling. | Refer to "Unit Short Cycles" (Mechanical Diagnostics). |
| Rapid cycling between Cool, Null, and Heat modes. | Air short cycling through evaporator. | Check and correct cargo load. |
| Defective controller or power module. | Diagnose power module and controller. Replace defective component. | |
| Short cycling. | Refer to “Unit Short Cycles” (Mechanical Diagnostics). | |
| Compressor Digital Control valve stuck close or defective. | Replace valve. | |
| Hot liquid line. | Shortage of refrigerant. | Repair or recharge. |
| Expansion valve open too wide. | Adjust or replace expansion valve. | |
| Frosted liquid line. | Liquid line restricted. | Remove restriction. |
| Restricted filter drier. | Replace filter drier. | |
| Frosted or sweating suction line. | Expansion valve admitting excess refrigerant. | Check feeler bulb and adjust expansion valve. |
| Evaporator coil needs defrosting. | Check defrost circuit including controller and evaporator coil sensor. | |
| Evaporator fan does not operate. | Refer to “Evaporator Fan Motor Does Not Operate” (Mechanical Diagnostics). | |
| Unit in vacuum - frost on expansion valve only. | Ice plugging expansion valve screen or orifice. | Apply hot wet cloth to expansion valve. Moisture indicated by increase in suction pressure. Replace filter drier. |
| High suction pressure. | Overcharge of refrigerant. | Purge system. |
| Expansion valve open too much. | Adjust or replace valve. | |
| Defective controller or power module. | Diagnose power module and controller. Replace defective component. | |
| Service gauge out of calibration. | Adjust or replace service gauge. | |
| Low suction pressure.
注意 This unit
has a digital capacity control system. Suction and discharge pressures
may drop below expected normal readings when the unit is in Modulation
Cool (control temperature within 10 C (18 F) of setpoint or in Power
Limit mode).
|
Shortage of refrigerant. | Repair leak and recharge. |
| Low ambient air temperature. | No remedy. | |
| Iced or dirty evaporator coil. | Defrost or clean evaporator coil. | |
| Restricted lines. | Locate and clear restriction. | |
| Plugged filter drier. | Replace filter drier. | |
| Expansion valve closed too much. | Adjust or replace valve. | |
| Expansion valve feeler bulb improperly mounted, poorly insulated or making poor contact. | Correct feeler bulb installation. | |
| Evaporator fans off. | Check evaporator fan motors and control circuit and correct fault. | |
| Defective controller or power module. | Diagnose power module and controller. Replace defective component. | |
| Service gauge out of calibration. | Adjust or replace gauge. |
| Condition | Possible Cause | Remedy |
|---|---|---|
| R-134a or R-23 System Compressor operating in a vacuum (unit not cooling) | Shortage of refrigerant | Repair leak and recharge |
| Compressor motor contacts frozen (R-134a compressor only) | Clean points or replace contactor | |
| Defective liquid line solenoid valve | Repair or replace liquid line solenoid valve | |
| Compressor inefficient | Repair or replace liquid line solenoid valve | |
| (R-134a compressor only) | Check valve reeds and pistons | |
| Partial obstruction in low side or dehydrator | Locate obstruction and repair | |
| Iced or plugged evaporator coil | Defrost or clean evaporator coil | |
| Expansion valve partially closed by ice, dirt or wax | Replace expansion valve | |
| Expansion valve power element lost its charge | Replace expansion valve | |
| Defective container insulation | Correct or replace container insulation | |
| Poor fitting container doors | Repair or replace doors | |
| Partial obstruction in high side | Locate obstruction and repair | |
| Suction pressure gauge out of calibration | Replace service gauge | |
| Expansion valve feeler bulb improperly mounted, poorly insulated or making poor contact | Correct feeler bulb installation | |
| Load temperature too high - unit not cooling. | One or both compressors do not operate | Refer to (Mechanical Diagnostics). |
| Controller setpoint too high. | Adjust controller setpoint. | |
| Defective controller or main relay board | Diagnose main relay board and controller. Replace defective component | |
| Shortage of refrigerant. | Repair leak and recharge. | |
| Overcharge of refrigerant. | Purge system. | |
| Air in refrigeration system. | Evacuate and recharge. | |
| Vapor injection valve open. | Check vapor injection valve circuit and compressor discharge temperature sensor. | |
| Too much compressor oil in system. | Remove compressor oil from compressor. | |
| Iced or dirty evaporator coil. | Defrost or clean evaporator coil. | |
| Restricted lines on high side. | Clear restriction. | |
| Plugged filter drier/in-line filter. | Change filter drier. | |
| Compressor inefficient (R-134a system only) | Perform compressor efficiency test. Check valve reeds and pistons | |
| Condenser coil dirty or airflow restricted. | Clean condenser coil, clear restriction, or repair or replace fan motor or condenser fan blade. | |
| Expansion valve power element lost its charge. | Replace power element. | |
| Expansion valve feeler bulb improperly mounted, poorly insulated or making poor contact. | Correct feeler bulb installation. | |
| Head pressure too low.
注意 This
unit has a digital capacity control system. Suction and discharge
pressures may drop below expected normal readings when the unit is
in Modulation Cool (control temperature within 10 C (18 F) of setpoint
or in Power Limit mode).
|
Shortage of refrigerant. | Repair leak and recharge. |
| Low ambient air temperature. (R-134a system only) | No remedy. | |
| Service gauge out of calibration. | Replace gauge. | |
| Compressor suction or discharge valve inefficient (R-134a system only) | Replace suction reeds and gaskets. Clean valve plate. If defective/restricted then replace. | |
| Head pressure too high. | Refrigerant overcharge. | Purge system. |
| Air in refrigeration system. | Evacuate and recharge. | |
| Dirty or restricted condenser coil. | Clean condenser coil. | |
| Condenser fan not operating. | Refer to “Condenser Fan Motor Does Not Operate” (Mechanical Diagnostics). | |
| Condenser fan grille damaged or missing. | Repair or replace grille. | |
| Condenser fan blade damaged. | Replace fan blade. | |
| High ambient air temperature. | No remedy. | |
| Restricted dehydrator or high side. | Replace filter drier or clear restriction. | |
| Defective service gauge. | Replace gauge. | |
| Compressor loses oil. | Refrigerant leak. | Repair leak and recharge. |
| Compressor oil migrates to system. | Short cycling. | Refer to "Unit Short Cycles" (Mechanical Diagnostics). |
| Rapid cycling between Cool, Null, and Heat modes. | Air short cycling through evaporator. | Check and correct cargo load. |
| Defective controller or power module. | Diagnose power module and controller. Replace defective component. | |
| Short cycling. | Refer to “Unit Short Cycles” (Mechanical Diagnostics). | |
| Hot liquid line. | Shortage of refrigerant. | Repair or recharge. |
| Expansion valve open too wide. | Adjust or replace expansion valve. | |
| Frosted liquid line. | Liquid line restricted. | Remove restriction. |
| Restricted filter drier. | Replace filter drier. | |
| Frosted or sweating suction line. | Expansion valve admitting excess refrigerant. | Check feeler bulb and adjust expansion valve. |
| Evaporator coil needs defrosting. (R-134a system only) | Check defrost circuit including controller and evaporator coil sensor. | |
| Evaporator fan does not operate. (R-23 system only) | Refer to “Evaporator Fan Motor Does Not Operate” (Mechanical Diagnostics). | |
| Unit in vacuum - frost on expansion valve only. | Ice plugging expansion valve screen or orifice. | Apply hot wet cloth to expansion valve. Moisture indicated by increase in suction pressure. Replace filter drier. |
| High suction pressure. | Overcharge of refrigerant. | Purge system. |
| Expansion valve open too much. | Adjust or replace valve. | |
| Defective controller or power module. | Diagnose power module and controller. Replace defective component. | |
| Service gauge out of calibration. | Adjust or replace service gauge. | |
| Low suction pressure.
注意 This unit
has a digital capacity control system. Suction and discharge pressures
may drop below expected normal readings when the unit is in Modulation
Cool (control temperature within 10 C (18 F) of setpoint or in Power
Limit mode).
|
Shortage of refrigerant. | Repair leak and recharge. |
| Low ambient air temperature. (R-134a system only) | No remedy. | |
| Iced or dirty evaporator coil. (R-134a system only) | Defrost or clean evaporator coil. | |
| Restricted lines. | Locate and clear restriction. | |
| Plugged filter drier. | Replace filter drier. | |
| Expansion valve closed too much. | Adjust or replace valve. | |
| Expansion valve feeler bulb improperly mounted, poorly insulated or making poor contact. | Correct feeler bulb installation. | |
| Evaporator fans off. | Check evaporator fan motors and control circuit and correct fault. | |
| Defective controller or power module. | Diagnose power module and controller. Replace defective component. | |
| Service gauge out of calibration. | Adjust or replace gauge. |