Fault maintenance of screw refrigeration unit

October 7, 2023

Fault Phenomenon 1: Failure to start or stop immediately after starting due to heavy starting load;

①, the energy adjustment is not to zero;

②. The misalignment between the compressor and the motor is too large;

③. Wear and burn in the compressor;

④. Power failure or low voltage (less than 10% of the rated value);

⑤. Improper adjustment of pressure controller or temperature sensor makes the contact normally open;

⑥. The differential pressure controller or relay is disconnected and not reset;

⑦, motor winding burned or open circuit;

⑧, contactor, intermediate relay coil burned or poor contact;

⑨. The temperature controller is improperly adjusted or faulty;

⑩, control circuit failure


Treatment methods:

①. Reduce the load to zero;

②. Re-align;

③. Disassembly and maintenance;

④. Eliminate circuit faults and supply power according to product requirements;

⑤. Adjust the contact position as required;

⑥. Press the reset button;

⑦, maintenance;

⑧. Dismantle and repair;

⑨. Adjust the setting value of the temperature controller or replace the thermostat;

⑩. Check and correct. breakdown


Phenomenon 2: Fault analysis of excessive vibration of the unit;

①. The foundation of the unit is not fastened;

②. The misalignment between the compressor and the motor is too large;

③. The natural vibration frequency of the unit and the pipeline is similar and resonates;

④. Inhale excessive liquid refrigerant.


Treatment methods:

①. Plug the adjusting gasket and tighten the foundation screw;

②. Re-align;

③. Change the position of pipeline support point;

④. Adjust the liquid supply. breakdown


Phenomenon 3: Failure analysis of abnormal sound in compressor operation:

①. Loose key of coupling;

②. The compressor and motor are misaligned;

③. Inhale excessive liquid refrigerant;

④. There are foreign bodies in the compressor;

⑤. The bearing is excessively worn or damaged.


Treatment methods:

①. Tighten bolts or replace keys;

②. Re-align;

③, adjust the liquid supply;

④, maintenance compressor and suction filter;

⑤. Replace.


Fault symptom 4: Failure analysis of high exhaust temperature:

①. Insufficient oil injection or liquid injection of compressor;

②, the oil temperature is too high;

③, inhalation overheating is too large.


Treatment methods:

①. Adjust the fuel injection amount or liquid injection amount;

②, see the fault analysis of high oil temperature;

③. Open the liquid supply valve appropriately to increase the liquid supply.


Fault phenomenon 5: Failure analysis of compressor body temperature is too high:

①. Excessive suction overheating;

②, parts wear caused by friction parts heating;

③. The exhaust pressure is too high;

④, the oil temperature is too high;

⑤. Insufficient fuel injection or liquid injection;

⑥, compressor burns due to impurities and other reasons.


Treatment methods:

①. Adjust the throttle valve appropriately;

②. Parking inspection;

③, check the high pressure system and cooling water system;

④. See the fault analysis;

⑤. Increase the fuel injection quantity or liquid injection quantity;

⑥. Parking inspection.


Fault phenomenon 6: Failure analysis of low evaporation pressure:

①. Insufficient refrigerant;

②. The throttle valve is too small;

③. The throttle valve is blocked by dirt or ice;

④. The drying filter is blocked;

⑤, solenoid valve is not open or failure;

⑥. The evaporator is frosted too thick.


Processing method;

①, add refrigerant to the specified amount;

②. Appropriate adjustment;

③. Cleaning and repair;

④. Cleaning and replacement;

⑤. Open and replace;

⑥, defrosting treatment.


Fault symptom 7: The pre-lubricating oil pump cannot generate enough oil pressure. Fault analysis:

①. The oil pipeline or oil filter is blocked;

②, insufficient oil (not up to the specified oil level);

③, oil pump failure;

④, oil pump rotor wear;

⑤. The pressure sensor is out of alignment.


Treatment methods:

①. Replace the filter element and clean the filter screen;

②. Add refrigerating machine oil to the specified value;

③. Inspection and repair;

④. Check and replace;

⑤. Adjustment and replacement.


Fault symptom 8: Noise of pre-lubricating oil pump Fault analysis:

①. Damage of coupling;

②. Loose bolt;

③. Damage of oil pump.



①. Replace

②. Re-tighten

③. Repair the oil pump.


Fault phenomenon 9: Fault analysis of high oil temperature:

①. For the water-cooled oil cooler (1) the cooling water temperature is too high (2) the water quantity is insufficient (3) the heat exchange tube scales;

②. The liquid spraying amount of the liquid spraying oil cooling system (1) is insufficient (2) the evaporation pressure corresponding to a certain high pressure is too high (3) the suction is too overheated (4) the filter in the liquid spraying pipeline is blocked (5) the servo solenoid valve does not act.


Treatment methods:

①. For the water-cooled oil cooler (1), reduce the cooling water temperature (2) increase the water volume (3) clean the heat exchange tube;

②.(1) Check the liquid level of the oil reservoir or condenser and the pressure in front of the nozzle for the oil spray cooling system ; (2) Reduce the evaporation pressure; (3) Adjust the system (4) Clean; (5) Adjust and maintain.



Shanghai KUB Refrigeration Equipment Co., Ltd.
Address : No. 328 on the 4th plant hengyong Road, Jiading District, Shanghai
Factory Address : No. 328 on the 4th plant hengyong Road, Jiading District, Shanghai
Work Time : 8:30-17:30(Beijing time)
Phone :

86-021 -63184860-17(Work Time)

86--13916495206(Nonworking time)

Fax : 86-021-53750132
Email : lucy@shkubao.com


Customer Manager
Mr mick Cai
Phone : +86 13588563336
WhatsApp : +86 13588563336
Skype : kub.mick
WeChat : CP9301
Email : kub02@shkubao.com
Miss. Mophy Mao
Phone : +86 15001938306
WhatsApp : +86 15001938306
WeChat : kub-maomao
Email : kub@shhkubao.cn


Mr Peter Huang
Phone : +86 15317830025
WhatsApp : +86 15317830025
Skype : kub-peter
WeChat : Shkub_01
Email : lucy@shkubao.com