Causes and Countermeasures for Refrigeration System Blockage

There are major causes for refrigeration system blockage: ice block or filth blockage in expansion valve, and filth blockage of drying filter. These blockages will hinder refrigeration circulation or cause failure or slow refrigeration, which leads to machine shutdown due to high and low pressure faults.

Causes and countermeasures for ice block

Causes:

As the continuous circulation of refrigerant, the excessive moisture contained in refrigeration system gradually gather at the expansion valve outlet, where the temperature is so low that moisture is turned into ice and becomes bigger. Then expansion valve outlet will be to some extent blocked, leading to failure of refrigerant circulation. The major sources of moisture include: 1, moisture contained in insulation paper of compressor motor; 2, residual moisture in parts and pipelines of system due to inadequate drying; 3, moisture contained in refrigerating machine oil and refrigerant; 4, moisture infiltrating system due to long time exposure to air during assembly and repair.

Faults description:

At the beginning of ice block, system can work normally and frosting starts to form on the surface of evaporator; along with the formation of ice block, the sound of expansion valve throttle faints slowly; when expansion valve is totally blocked, throttle sound dies away and little fluid flow inside copper pipe. No heat exchange of condenser and surface temperature drops down. On the other hand, compressor is still on the running and discharge pressure continues to rise (detect via high-pressure manometer). Low pressure side has been vacuummiezd to cause low pressure faults (detect via low-pressure manometer).

Trouble-shooting:

For the minor ice block, hot towel can be used to spread at the block site to melt ice; for the serious problem of ice block and system has been affected, it is necessary to replace drying filter, re-handle pipelines, fulfill pumping and refill refrigerant.

Causes and countermeasures for filth blockage

Causes:

Filth blockage faults are often caused by excessive impurities in system. They mainly stem from: 1, not completely removing dusts and scraps during making copper pipes and oxide layer stick to pipe inwall when welding; 2, impurities contained in refrigerating machine oil and refrigerant; 3, dusts inside drying filter entering pipeline.

Faults description:

If filth blockage takes place in system, refrigerant will fail to circulate while compressor is on the continuous running. The surface of evaporator is not cold and condenser not hot, compressor shell is not hot while there is no airflow sound inside evaporator. High pressure continues to rise and low pressure drops gradually. If it is the partial blockage, you may sense cool or ice-cold on the evaporator surface but frosting does not exist. When drying filter is blocked, you can feel cool when touching it and even frosting would be formed. The difference between filth blockage and ice block is that, refrigeration can be resumed when filth blockage while refrigeration can be resumed when ice block because ice can be melt.

Trouble-shooting:

Generally, filth blockage takes place with drying filter. For the minor blockage, to replace it with a brand-new filter is the solution. For much impurities in system and operation has been affected, it is imperative to clear system and replace drying filter, vacummizing and refilling refrigerant.