ABOUT US

Home page

Company Profile

Research and Innovation

Honor and Partners

On-site Construction

Development History

News Center

The cold storage unit shut down before reaching the correct temperature? Don't rush to call a technician; first consider these 8 possible reasons.

Update time:

2026-04-29

The most frustrating thing about opening a cold storage room is when the compressor suddenly shuts down before the temperature reaches the set value. The customer is in a hurry, hot air rushes in when the door is opened, the repairman says it will take several days, and the owner is anxiously wringing his hands. Actually, 70% of these problems are caused by common minor issues. Today, we'll break it down and discuss why a cold storage room shuts down before reaching the set temperature, providing practical troubleshooting methods that even ordinary people can use, and finally, how to reduce this situation from the root.

I. Understanding the Principle: Why Does the Cold Storage Shut Down Before Reaching the Set Temperature?

Normally, the cold storage compressor works like this: the temperature sensor detects that the internal temperature is higher than the set value (e.g., -18℃), and starts the compressor to cool; when the temperature drops to near the set value (e.g., -18±1℃), the compressor automatically shuts down. However, if it shuts down before reaching the set temperature, it means the system is "misinterpreting" the situation or has encountered a forced shutdown signal.

In simple terms, the problem could be either inaccurate temperature measurement (sensor issue), incorrect pressure (abnormal high/low pressure), or a triggered protection mechanism (such as overload or phase loss). Check the following specific reasons to see how many apply to your cold storage.

II. 8 Common Causes – Troubleshooting Them Yourself First

1. Temperature Sensor Malfunction: Incorrect Installation or Faulty

The sensor is like the "eyes" of the cold storage. If it measures inaccurate temperatures, the compressor will receive incorrect commands. There are two common scenarios: First, the sensor is installed too close to the air outlet (where the temperature is lowest), or against the inner wall of the cold storage (highly affected by external factors), measuring a temperature much lower than the actual temperature inside the storage, causing the system to mistakenly believe the target temperature has been reached and shut down. Second, the sensor may be worn out from prolonged use, with poor contact or a dirty probe, resulting in fluctuating readings.

For example: A customer once said his cold storage was set to -15℃, but the compressor would stop after running for half an hour. Upon inspection, it was found that the sensor was frozen 5 cm below the air outlet, where the temperature was only -20℃, causing the system to shut down prematurely.

2. High and Low Pressure Protection Too Sensitive: Abnormal Pressure Triggers Shutdown

Cold storage relies on the compressor to compress the refrigerant, creating high-pressure and low-pressure cycles. If the high pressure is too high (e.g., poor condenser heat dissipation, pressure exceeding 2.5 MPa) or the low pressure is too low (e.g., refrigerant leakage, pressure below 0.2 MPa), the protection device will directly cut off the power. Sometimes, even if the pressure gauge needle hasn't reached its limit, excessive fluctuations can trigger the protection.

Tip: After shutting down, wait 10 minutes and observe whether the pressure gauge returns to the normal range (high pressure is generally 1.2-2.0 MPa, low pressure 0.4-0.8 MPa). If the pressure gauge needle jumps wildly, or the pressure doesn't drop after shutdown, this is likely the problem.

3. Compressor Overload Triggering Frequently:

Prolonged continuous operation and heavy loads (e.g., high storage temperature, frequent door openings) can cause the compressor to overheat and trigger overload protection. This is especially true in summer when ambient temperatures exceed 35°C, as poor heat dissipation exacerbates the problem. Additionally, poor compressor lubrication (e.g., insufficient refrigerant oil) increases operating resistance, further straining the motor.

Note: If the compressor casing is extremely hot to the touch after shutdown (normal temperature is around 60-80°C; temperatures above 90°C indicate a problem), it's almost certainly due to overheat protection activation.

4. Power Supply Issues: Unstable Voltage or Phase Loss

Cold storage compressors are highly sensitive to voltage, generally requiring a stable 380V three-phase power supply. If the voltage drops below 340V (or a single-phase voltage below 200V), the compressor may fail to start. More commonly, a phase loss (e.g., a poor connection in one of the three-phase wires) can cause a sudden drop in power, leading to a surge in current and tripping the protection device.

Self-check method: Use a multimeter to check if the three-phase voltage is balanced (the voltage difference between the three phases should not exceed 10V), or observe whether the circuit breaker in the electrical box trips frequently. If a phase voltage is found to be significantly lower, it may be due to aging wiring or loose connections.

5. Insufficient refrigerant: Leaks lead to decreased cooling efficiency

Refrigerant (such as Freon) is the "blood" of cold storage refrigeration. If there is a leak in the pipes, the refrigerant will slowly leak out, and the compressor will not be able to lower the temperature no matter how hard it tries. Initially, it may still be able to cool, but as the refrigerant decreases, the temperature in the cold storage will not reach the set value for a long time, and the compressor will run at high load for a long time, eventually triggering a protective shutdown.

Tip for judging: Open the cold storage door and smell it. If there is a faint pungent odor (a slight odor may be present due to a refrigerant leak), or listen for a hissing sound at the pipe joints (you need to listen carefully). Of course, the most accurate way is to have a professional use a leak detector.

6. Evaporator "Excessive Frost": Reduced Heat Exchange Efficiency

The evaporator is the main heat absorber in a cold storage unit. If the frost on its surface is too thick (more than 5 mm), cold air circulation is obstructed, and heat exchange efficiency drops significantly. At this point, although the compressor is still running, the cooling effect deteriorates, the storage temperature fails to drop, and the system may mistakenly identify a "malfunction" and shut down.

Especially in air-cooled cold storage units, if the fan is broken or the air ducts are blocked, the evaporator will frost up even faster. Observe the evaporator surface; if it is covered with white frost and unevenly distributed (with particularly thick areas), defrosting is necessary.

7. Condenser "Poor Heat Dissipation": Dust Blockage or Fan Failure

The condenser's function is to cool the high-temperature, high-pressure gas discharged from the compressor into a liquid. If heat dissipation is poor, the high pressure will spike, triggering a protective shutdown. Common causes include a buildup of dust or pollen on the condenser surface (especially in outdoor units), or a damaged or slowed-down fan motor.

Inspection Method: Open the condenser protective mesh and shine a flashlight inside. If there are almost no gaps between the heat sink fins (they're covered in dust), or the fan spins very slowly or doesn't spin at all, this is where the problem lies.

8. Control System "Glitch": Relay or Motherboard Failure

The control panel of a cold storage unit is like its "brain." If the relay contacts inside are oxidized or the motherboard program malfunctions, it may issue incorrect shutdown commands. This situation is usually quite subtle; for example, the compressor's running time may be irregular (sometimes it runs normally for half an hour, sometimes it stops immediately after starting), or it may be unable to restart after stopping.

Tip: If all other hardware has been checked and is working properly, but the problem persists, it's most likely a problem with the control system, requiring professional troubleshooting.

III. Xiangning Refrigeration's Practical Advice: Reduce Downtime Issues from the Source

Frankly, cold storage is a "delicate" system, but many problems can actually be avoided through routine maintenance. When we at Xiangning Refrigeration customize cold storage solutions for our clients, in addition to designing reasonable unit matching schemes, we always repeatedly remind them to pay attention to these details:

**Conduct a comprehensive inspection at least once a year:** This includes pressure gauge calibration, refrigerant pressure testing, and electrical wiring insulation testing. Don't wait until problems arise to panic.

**If your cold storage unit is shutting down before reaching the required temperature, first check the above steps yourself. If you can't resolve the issue, don't force it—after all, substandard cold storage temperatures not only result in electricity bills but also damage to the quality of your goods. Find a reliable cold storage service provider (like Xiangning Refrigeration) to resolve the problem once and for all; it's much more worry-free than repeated repairs.

**Remember, cold storage is not equipment that can be turned on and then ignored.** Paying attention to details is crucial for ensuring it serves you reliably.

**Sensor installation location:** It must be away from air vents and inner walls, installed in a location with even airflow within the storage area (usually 1.5-2 meters from the ground and at least 20 centimeters from the wall).

Regularly clean the condenser: Especially in summer, clean the dust with a soft brush every two weeks, and lubricate the fan bearings annually.

Avoid frequent door opening: Especially in summer, try to limit door opening time to within 30 seconds, and use an insulated curtain to block the flow of goods when loading or unloading.