Today Corun has summarized five common problems of refrigeration system that people normally find on their transport refrigeration units or air conditioners, analyzed the causes and provided with corresponding solutions. Trust this article is useful to many people and you are welcome to share the article to people who may need it.

Insufficient Refrigerant

1. Phenomena

Cooling performance of the unit is poor, the drainage outlet is just a little cool, the pressure values tested by manifold pressure gauge at high pressure and low pressure both sides are too low, and bubble flow can be seen from the sight glass.

2. Cause

Refrigerant leakage causes the shortage of refrigerant.

3. Troubleshooting

1) Find the leakage point by electronic leak detector, then repair or replace the parts.

2) If no parts are replaced, add moderate refrigerant; if parts are replaced, add moderate refrigerant oil and fill in enough refrigerant after vacuuming the system.

Excessive Refrigerant

1. Phenomena

Cooling performance of the unit is poor, the pressure values tested by manifold pressure gauge at high pressure and low pressure both sides are too high, and bubble flow cannot be seen from the sight glass.

2. Cause

    The unit cannot give full play of cooling capacity due to excessive refrigerant.

3. Troubleshooting

Connect the manifold pressure gauge to the system, slowly loosen the manual valve at the low pressure side of the gauge, and slowly discharge the refrigerant (refrigerant cannot be discharged from the high pressure side as refrigerant will bring out a lot refrigerant oil if it comes out from high pressure side) until the pressure values at both sides return back to normal, clear refrigerant flow and occasional bubble flow can be seen from the sight glass.

Air Enters into Refrigeration System

1. Phenomena

Cooling capacity of the unit drops. After testing by manifold pressure gauge, it is found that the pressure at the high pressure side is on a higher side, pressure at the low pressure side sometimes is higher than normal. Besides, a lot of bubble flows can be seen from the sight glass.

2. Cause

Air enters into the system. Vacuuming is not carried out completely after assembling or overhauled; air is brought into the system while filling in the refrigerant or refrigerant oil; air enters through openings while system is working in negative pressure. Air has a certain pressure, and refrigerant has a certain pressure. In a closed container, the gas pressure is the total of all partial pressures, so the pressure readings are higher than normal values.

3. Troubleshooting

1) Discharge some refrigerant (slowly discharge from the low pressure side by the use of pressure gauge)

2) Check the cleanliness of the compressor oil.

3) Refill the refrigerant after vacuuming.

Ice Blockage in Refrigeration System

1. Phenomena

The refrigeration system sometimes cools, sometimes does not cool. During its operation, the pointer of the low pressure side on the manifold pressure gauge fluctuates frequently between negative pressure and normal value.

2. Cause

    Water is mixed into the refrigerant. Water and refrigerant are immiscible, so when refrigerant passes the throttle holes of the expansion valve, the temperature drops suddenly, hence the water mixed with the refrigerant will become very little spherical or semi-spherical ice particles inside or around the throttle holes. If these ice particles accumulate to certain degree, the throttle channel is blocked. When ice blockage is formed, the refrigeration system cannot work normally and cooling performance drops obviously.

When low pressure meter shows negative pressure, the temperature around ice blockage increases and ice particles melt. Refrigeration system is restored to normal work. When the pressure at low pressure side returns to normal, ice blockage again is formed and system malfunctions.

3. Troubleshooting

1) The drier is in hyper saturated state, so it is a must to replace the reservoir with drier and fill in 30ml refrigerant oil.

2) Vacuum the system and fill in refrigerant in specified amount.

Filth Blockage in Refrigeration System

1. Phenomena

The unit has poor cooling performance or does not cool at all. During the system operation, the readings of high and low pressure meters on the manifold pressure gauge are both lower than normal values. Besides, frosting or condensation is formed on the filter and the front and rear pipes of the capillary.

2. Cause

The dust in the refrigeration system is bonded to or attached to the filter net at the filter inlet, or at the interface of the capillary and the filter net, making this position a local throttle phenomenon. The temperature drops rapidly, forming frosting or condensation.

3. Troubleshooting

The filter net of the filter inlet is considered blocked if frosting is formed at the filter inlet, intermittent sound of airflow can be heard, and when using a wrench to strike gently the filter, the sound of airflow changes and the frosting melts.

You should:

1) Remove the capillary, clean the filter net, blow it dry, and restore it. Or replace a filter.

2) Vacuum the system and fill in refrigerant in specified amount.

Again, if you are not a professional technician, please leave the job to Corunclima trustworthy dealers.