Five common problems of refrigeration system

Five common problems of refrigeration system

1. Treatment of insufficient refrigerant

1. Trouble phenomenon: The cooling effect of the whole machine is poor, the water outlet is only slightly cool, and the pressure on the high pressure side and the low pressure side are found to be low when checked with the manifold pressure gauge (under the normal speed of the compressor, when the ambient temperature is about 35 ℃, the low pressure The table index is lower than 1kg/cm2, and the high-pressure table index is lower than 10kg/cm2), while the flow of bubbles can be seen in the sight glass.

　　2. Reason for failure: There is a refrigerant leak in the refrigeration system, which leads to insufficient refrigerant.

　　3. Treatment method: 1). Use an electronic leak detector to find out the leak and repair or replace parts.

　　2) If the parts are not replaced, only a proper amount of refrigerant can be added; if the parts are replaced, a proper amount of refrigerating oil should be added as required, and the system should be evacuated to add enough refrigerant.

　　 2. Overcharge of refrigerant

　　1. Failure phenomenon:

The refrigeration effect is poor. When checking with the manifold pressure gauge, it is found that the pressure on the high pressure side and the low pressure side are too high (when the compressor speed is normal and the ambient temperature is 35℃, the pressure of the high pressure gauge is about 19kg/cm2 and the pressure of the low pressure gauge is 2.3 kg/cm2, and no bubbles flow in the sight glass.

　　2. Reason for the failure: too much refrigerant in the refrigeration system, which makes the refrigeration capacity unable to fully play, resulting in poor refrigeration effect.

3. Treatment method: Connect the manifold pressure gauge to the system, and slowly loosen the manual valve on the low pressure side of the manifold pressure gauge to allow the refrigerant to be discharged slowly (not from the high pressure side, because the refrigerant will be discharged from the high pressure side. A large amount of refrigerating oil) until the pressure on the high and low sides is normal, and the refrigerant can be seen from the sight glass to flow clearly, and occasionally there are bubbles flowing through.

　　 3. Air is mixed into the refrigeration system

1. Trouble phenomenon: The refrigeration capacity of the whole machine is reduced; when checking with the manifold pressure gauge, it is found that the pressure on the high pressure side is too high, and the pressure on the low pressure side is sometimes higher than the normal value (when the compressor speed is normal, the ambient temperature is 35°C When the pressure on the high-pressure side is higher than 20kg/cm2; and the pointer of the high-pressure meter is oscillating; on the other hand, many bubbles flow can be seen in the sight glass.

　　2. Reason for failure:

　　 Air is mixed into the system. Mainly after assembly or overhaul, the vacuum is not complete; when charging refrigerant or adding refrigerating oil, air is brought into the system, or when the system is working under negative pressure, air is mixed in through improper places. When air enters the refrigerant, it has a certain pressure, and the refrigerant also has a certain pressure. In a closed container, the total gas pressure is equal to the sum of the partial pressures, so the high and low pressure gauges are higher than the normal value.

　　 3. Treatment method: 1) Release the refrigerant (slowly release from the low pressure side with a pressure gauge). 2) Check the cleanliness of the compressor oil. 3) Refill refrigerant after vacuuming.

　　 4. "Ice blockage" in the refrigeration system

　　1. Trouble phenomenon: The refrigeration system periodically refrigerates suddenly and does not refrigerate. During operation, the pointer on the low pressure side of the manifold pressure gauge often fluctuates between the negative pressure and the normal value.

2. The cause of the fault: The refrigerant in the refrigeration system is mixed with moisture. Because moisture and the refrigerant are incompatible, when the refrigerant flows through the orifice of the expansion valve, the temperature drops suddenly, and these are mixed in the refrigerant The moisture in the throttle valve easily forms very small ice particles around the orifice of the throttle valve or the valve needle hole, which are spherical or hemispherical. When the ice particles condense to a certain extent, they block the throttle channel and form an ice block failure. . When icing causes ice blockage, the refrigeration system cannot work normally, the refrigeration effect is obviously reduced, or even no refrigeration.

　　 At this time, the low pressure gauge has negative pressure, so the temperature at the ice block rises obviously, the ice particles in the ice block melt into water, the ice block phenomenon disappears, the refrigeration system resumes normal operation, the refrigeration is good, and the low pressure side pressure returns to normal. After a while, the system was blocked by ice again, and the system was not working properly.

　　 3. Treatment method: 1) Because the desiccant is in a supersaturated state, it is necessary to replace the reservoir with the desiccant and add 30ml of refrigerating oil. 2) Vacuum the system and add a specified amount of refrigerant.

　　 5. Dirty blocking troubleshooting

　　 1. Trouble phenomenon: poor cooling effect or no cooling. When the air-conditioning system is running, the readings of the high/low pressure gauges on the manifold pressure gauge are less than normal. (When the compressor speed is normal and the ambient temperature is about 35℃, the pressure on the high pressure gauge side is lower than 9kg/cm2, and the pressure on the low pressure side is at Negative pressure state), and there is frost or condensation on the filter and the pipes before and after the capillary tube.

2. The cause of the failure: The dust in the refrigeration system is stuck or attached to the filter at the inlet of the filter, or at the interface between the capillary and the filter, causing a local throttling phenomenon at this position, and the temperature drops rapidly, and condensation or condensation occurs. Frost.

3. Treatment method: If there is frosting at the inlet of the filter, and you hear intermittent airflow sound, tap the filter body with a small wrench, the airflow sound will change, and the frost layer in front of the filter and capillary will melt, which can be judged The filter inlet filter is blocked.

　　At this time: ①Remove the capillary tube, clean the filter screen and blow dry, and reinstall it. Or replace the filter ②, vacuum, and add refrigerant to the specified amount.