Maintenance and repair of key components of refrigerated trucks（3）

Maintenance and repair of key components of refrigerated trucks（3）

The refrigeration unit consists of an engine system, a refrigeration system, backup power and electrical control devices. The reasons and troubleshooting methods for compressors running normally but not cooling are mainly as follows:

The filter is clogged, which means that there is refrigerant in the filter inlet, but no refrigerant leaks when the screw of the liquid outlet is loosened; the thermal expansion valve is blocked, and the manifestations are dirty and ice plugs.

Check the cold air motor insurance and load distributor, if damaged, replace it in time. The refrigeration system is not cooling well, and the temperature in the cargo box cannot reach the expected cooling effect. Insufficient refrigerant is manifested as slow cooling, and the liquid in the sight glass is in an intermittent flow state, mainly due to the low suction pressure; the thermal expansion valve is adjusted too large or too small. When the compressor is too large, the compressor will be wet and the The hourly suction pressure is low, and the frost formation is small; the surface of the condenser is too dirty, causing the air passage to be blocked, which is manifested by the high exhaust temperature and poor condensation effect; the surface of the evaporator is blocked by carton dust or other dirt, and the cold air is blocked; The speed of the evaporator cold wind motor is not enough, which is manifested by the weakening of the wind and the too small air volume.

The reason for both high pressure and low pressure is insufficient refrigerant. As long as the air conditioner is turned on, there will always be bubbles in the glass eyes; high and medium temperatures are low, and low temperatures are high, just add refrigerant. There is air in the refrigeration system. Check the system for leaks, adjust the expansion valve to achieve the best cooling effect; clean the condenser to improve the condensing effect; clean the evaporator, remove dirt, and reduce the cold air resistance; check whether the voltage of the air cooler and the motor is lower than 12V, if If yes, check the 12V alternator and load splitter; if the alternator is faulty, the rectifier regulator tube in the generator may be damaged. When the generator is replaced unconditionally, the voltage regulator of a domestic car can be used instead; if If the load distributor is damaged, replace it in time or choose a suitable high-power diode instead of the load distributor; also release the air in the system from the three-way valve of the liquid storage tank.