Video: Common Faults of Cold Storage (with a List of Fault Repair Methods)
Figure 1: Cold storage warehouse.
Cold storage is an indispensable and important facility in many industries. They play a key role in storing and
preserving various products. However, even with the most sophisticated systems, cold storage can suffer from various
failures. Not only do these failures result in product loss, they can also have a serious impact on a business's
operational efficiency and reputation. Therefore, timely identification and resolution of cold storage failures
becomes critical.
In this article, we will discuss the analysis and troubleshooting methods of common failures in cold storage.
Whether you are a cold storage supervisor, maintenance person, or business owner, this article will provide you with
useful information to help you better understand and respond to the challenges of cold storage failure.
Please note that the complexity and variety of cold storage failures means that this article cannot cover every
possible scenario. However, we will highlight some common failures and provide general solutions to help you better
cope and troubleshoot.
1. Analysis and Troubleshooting of Common Faults in Cold Storage
1.1 No Power on the Distribution Box
【Solution】: There is no power on the distribution box or the display screen does not work. Please check whether the special switch of the cold storage is malfunctioning (check the power supply and distribution box).
1.2 Poor Cooling Effect
【Solution】:
1. Check whether the condenser of the refrigerating machine is dirty.
2. Check whether there is too much frost on the evaporator in the warehouse.
3. Check whether the refrigerant is leaking (coat the pipe connections with soapy water, if bubbles are generated,
it indicates refrigerant leakage). And ask professionals to recharge the refrigerant and deal with leaks.
4. Check whether the seal of the cold storage door is intact.
5. Check whether the refrigerating machine in the cold storage is working.
6. Check whether the parameter settings of the cold storage computer controller are correct and readjust them.
7. Check whether the cold storage controller is malfunctioning and replace it.
8. Check whether there are enough gaps between the items stacked in the warehouse and adjust.
Figure 2: Parts diagram of refrigeration unit.
1.3 Abnormal Noise When Machine Running
【Fault Analysis and Solutions】
1. If there is abnormal noise when the machine is running, please stop the machine and check whether it is caused by
vibration or mechanical failure.
2. If there is abnormal noise in the distribution box, this is the sound emitted by the AC contactor. It is due to the damage of the contactor, the
inflexibility of the moving armature, and the dirt on the suction surface of the armature. Please restart the
contactor or remove the contactor and clean it to eliminate the noise.
1.4 Refrigerating Machine Starts Frequently
The refrigerating machine starts frequently or does not start for a long time, or does not stop when it is turned on
for a long time, or it stops when the set storage temperature is not achieved.
【Solution】:
1. Check whether there is dirt on the condenser. Poor heat dissipation will cause the condensation pressure of the
refrigerating machine to be too high. In order to protect the compressor, the machine will stop running under the action
of the pressure controller. After the heat dissipation is good, press the black reset button on the pressure
controller, the machine can automatically resume operation.
Do not adjust the setting value on the pressure controller arbitrarily, otherwise the pressure controller will not
be able to protect the machine.
2. The parameter setting of the controller is wrong, just reset it.
3. Cooling effect is not good and please refer to the above content of “poor cooling effect".
4. Temperature control failure, and replace it.
5. Electrical appliances are damaged, and replace the corresponding devices.
Figure 3: Pressure control.
1.5 Lamp in the Cold Storage is Not On
【Solution】: Please check whether the switch is malfunctioning and whether the bulb is damaged. Cut off the power supply during inspection, and pay attention to the waterproofness of the lamp when installing the lampshade.
1.6 Refrigerant Leak
【Fault Analysis】After the refrigerant leaks in the system, the cooling capacity is insufficient, the suction and
discharge pressures are low, and an intermittent "squeaking" air flow sound that is much louder than usual can be
heard at the expansion valve.
There is no frost or a small amount of floating frost on the evaporator.
If the expansion valve hole is enlarged, the suction pressure will not change significantly.
After shutdown, the equilibrium pressure in the system is generally lower than the saturation pressure corresponding
to the same ambient temperature.
【Troubleshooting method】After refrigerant leaks, do not rush to fill the system with refrigerant. Instead, you
should immediately find the leakage point and repair it before filling the system with refrigerant.
1.7 Too Much Frost on the Evaporator Surface
【Fault Analysis】 The cold storage evaporator that has been used for a long time must be defrosted regularly. If it
is not defrosted, the frost layer on the evaporator pipe will accumulate thicker and thicker. When the entire pipe
is wrapped by a transparent ice layer, it will seriously affect the heat transfer. As a result, the temperature in
the warehouse does not drop to the required range.
【Troubleshooting method】 Stop the machine for defrosting and open the door to allow air to circulate. You can also
use a fan to speed up circulation and reduce defrosting time.
Figure 4: Cold room air coolers.
2. List of Main Reasons and Troubleshooting Method of Other Cold Storage Problems
Temperature Does Not Drop in the Cold Storage
【Main reason】:
1. The warehouse door is not tightly closed.
2. The frost on the air cooler is too thick.
3. Low compressor efficiency.
4. The expansion valve is improperly adjusted or blocked by ice.
5. The expansion valve or the filter is dirty and clogged.
6. Refrigerant in the system decreases.
7. Oil stains on the inner wall of the copper pipe.
【Troubleshooting method】:
1. Adjust the gap in the warehouse door.
2. Defrost.
3. Repair or replace.
4. Readjust or replace the moisture absorbent.
5. Disassemble and wash.
6. Add refrigerant.
7. Flush with nitrogen.
Discharge Pressure Too High
【Main reason】:
1. The cooling water (air) volume of the unit is insufficient.
2. Excessive dirt on the condenser affects heat dissipation.
3. There is air in the system.
4. Too much refrigerant.
【Troubleshooting method】:
1. Find out the cause and make the air volume (water volume) normal.
2. Clean it.
3. Release the air.
4. Release excess refrigerant.
Discharge Pressure Too Low
【Main reason】:
1. Insufficient refrigerant.
2. There is leakage in the discharge valve.
【Troubleshooting method】:
1. Recharge the system with refrigerant.
2. Repair or replace.
Figure 5: Refrigeration unit maintenance.
Too High Suction Pressure
【Main reason】:
1. The expansion valve is opened too largely.
2. The compressor suction valve is leaking.
【Troubleshooting method】:
1. Readjust.
2. Repair or replace.
Too Low Suction Pressure
【Main reason】:
1. The expansion valve is opened too small or blocked.
2. There is insufficient refrigerant in the system.
3. The refrigerant is impure mixed with too much lubricating oil.
【Troubleshooting method】:
1. Adjust and eliminate blockage.
2. Add refrigerant.
3. Replace the refrigerant and check the oil return volume of the oil separator.
Compressor Does Not Start
【Main reason】:
1. Power outage, low voltage, or circuit failure.
2. The starter has poor contact.
3. The temperature controller fails.
4. The pressure controller is out of adjustment or malfunctioning.
【Troubleshooting method】:
1. Check the line.
2. Repair or replace.
3. Repair or replace.
4. Repair or replace.
Compressor Suddenly Stops During Operation
【Main reason】:
1. The suction pressure is too low, and the low-voltage relay
operates to cut off power.
2. The discharge pressure is too high, and the high-voltage relay operates to cut off power.
3. The motor overheats and the thermal relay operates to cut off power.
【Troubleshooting method】:
1. Clear the clogged pipes and add the refrigerant.
2. Check the cooling water (air) volume and press the high-pressure reset button.
3. Check whether the voltage is too low and the cooling load is too large.
Figure 6: Cold storage compressor.
Compressor Doesn't Stop
【Main reason】:
1. The control system fails or is in poor working condition.
2. The compressor suction and discharge valves are leaking.
【Troubleshooting method】:
1. Overhaul the control system and adjust pressure and temperature parameters.
2. Repair or replace.
Noisy Compressor
【Main reason】:
1. The compressor base is loose.
2. Liquid slugging.
3. Compressor parts are worn.
【Troubleshooting method】:
1. Fasten.
2. Close the liquid supply valve a little.
3. Replace.
Pressure Gauge Pointer Jumps
【Main reason】:
1. There is air in the system.
2. The pointer is loose.
3. The meter valve is opened too largely.
【Troubleshooting method】:
1. Release air.
2. Replace.
3. Close it a little.
Expansion Valve Ice Blocked
【Main reason】:
The refrigerant contains high water content.
【Troubleshooting method】:
Replace moisture absorber.
Expansion Valve Dirty and Clogged
【Main reason】:
There is dirt in the system.
Figure 7: Installation location of expansion valves in refrigeration unit.
【Troubleshooting method】:
Clean the system and expansion valve filter.
Expansion Valve Makes a Hissing Sound
【Main reason】:
1. Insufficient refrigerant.
2. The liquid is not supercooled and the resistance of the liquid pipe is too large.
【Troubleshooting method】:
1. Add.
2. Find out the reason and make the liquid have sufficient supercooling degree.
Expansion Valve Doesn't Work
【Main reason】:
1. The working fluid of the temperature sensing bulb leaks.
2. The throttling orifice and inlet are blocked.
【Troubleshooting method】:
1. Repair or replace.
2. Repair or replace.
Solenoid Valve Won't Close
【Main reason】:
1. The small hole in the valve body is blocked.
2. The spring fails.
【Troubleshooting method】:
1. Clean.
2. Replace.
Poor Solenoid Valve Sealing
【Main reason】:
1. There is dirt.
2. The sealing ring is worn.
3. Valve pressure is too low.
【Troubleshooting method】:
1. Clean.
2. Replace.
3. Readjust.
