In the fields of scientific research experiments and product quality inspection, constant temperature and humidity test chambers are indispensable equipment. They can simulate a variety of complex environments and provide precise test data for industries such as materials, electronics, and food. However, the problem of temperature and humidity runaway during use occurs from time to time. This not only leads to experimental failure and invalid product test results but also may cause sample damage. So, what should we do when encountering this situation?

I. Common Manifestations of Temperature and Humidity Runaway
Before analyzing the solutions, let’s first clarify the typical symptoms of temperature and humidity runaway. The test chamber may experience a continuous increase or decrease in temperature, far exceeding the set range. The humidity may either fail to reach the preset value or fluctuate violently. Even after turning off the humidification or dehumidification function, the humidity may still change continuously. In addition, the display screen of the test chamber may pop up error codes or alarm prompts. These are all signs that the equipment is “calling for help” and requires our timely response.
II. Accurate Identification of the Root Causes of Runaway
(1) Sensor Failure
Sensors are the “eyes” of the test chamber for sensing temperature and humidity. Once they have problems, the equipment will become “blind.” After long-term use, the sensor surface may adsorb dust, water vapor, or corrosive substances, resulting in reduced sensitivity and measurement deviations. For example, a humidity sensor that gets damp may misjudge an actual humidity environment of 60% RH as 80% RH, thereby causing the equipment to regulate incorrectly. Moreover, sensor aging, loose or damaged wiring can also prevent it from transmitting data normally, leading to temperature and humidity runaway.
(2) Abnormalities in the Refrigeration/Heating System
The refrigeration system is key to controlling temperature. Compressor failure, refrigerant leakage, or severe dust accumulation on the condenser can all affect the cooling effect. If the compressor has problems such as cylinder seizure or shaft seizure, it cannot compress the refrigerant normally, making it difficult to lower the temperature of the test chamber. Refrigerant leakage will result in insufficient refrigerant in the cycle, greatly reducing the cooling capacity. On the heating system side, burnt-out heating elements or heating controller failure can lead to inability to heat normally, or slow and unstable heating.
(3) Humidification/Dehumidification System Failure
Common problems in the humidification system include lack of water in the humidifier, scaling and blockage of the humidification pipe, and solenoid valve failure. For example, with an ultrasonic humidifier, calcium and magnesium ions in the water will deposit over time, forming a thick layer of scale inside the humidification pipe, preventing the mist from being sprayed out and preventing the humidity from rising. Dehumidification system failures are often related to ice formation on the condenser tube and poor drainage. Ice formation on the condenser tube affects heat exchange efficiency and reduces dehumidification effectiveness. Clogged drainage pipes prevent condensate from being discharged, causing the humidity inside the test chamber to remain high.
(4) Control System Failure
The control system of the test chamber is like the “brain,” responsible for receiving sensor signals and directing the operation of various components. If the control circuit board has a short circuit, component damage, or the control program has errors, it will result in “chaotic command.” For example, the program may misjudge sensor data and incorrectly start or stop the refrigeration and humidification equipment, thereby causing temperature and humidity runaway. In addition, improper operation, such as not correctly setting temperature and humidity parameters or frequently changing the set values, can also interfere with the normal operation of the control system.
(5) Environmental Factor Influence
The external environment in which the test chamber is located has a significant impact on its performance. When the ambient temperature is too high or too low, it increases the burden on the equipment for cooling or heating, making temperature and humidity regulation difficult. For example, placing the test chamber in a location with direct sunlight or near a heat source (such as a radiator or oven) will increase the external temperature of the chamber body, affecting internal temperature control. High ambient humidity can also cause condensation on the outer shell and door seams of the test chamber, which can enter the interior and interfere with humidity stability.
III. Step-by-Step Efficient Problem Solving
(1) Preliminary Inspection and Restart
Upon discovering temperature and humidity runaway, first check whether the power connection of the test chamber is normal and whether the equipment has any abnormal sounds or odors. If everything appears normal, try turning off the device’s power, wait for 5 – 10 minutes, and then restart it to see if it is due to temporary program errors causing the runaway. After restarting, reset the temperature and humidity parameters and observe the operation of the equipment.
(2) Sensor Calibration and Replacement
If the restart is ineffective, the sensors need to be calibrated. Use a high-precision standard temperature and humidity meter to compare with the measurement values of the sensors inside the test chamber. If the deviation exceeds the allowable range (generally ±0.5℃ for temperature and ±3% RH for humidity), then calibrate according to the equipment manual. If the calibration is still inaccurate, or the sensor is obviously damaged or aged, it is necessary to replace it with a sensor of the same model in a timely manner.
(3) In-depth System Inspection
Check the refrigeration, heating, humidification, and dehumidification systems in turn. Check whether the compressor is running normally and listen to whether its operating sound is stable; observe whether there is oil on the surface of the refrigerant pipe (oil stains may indicate a leakage point); clean the dust and debris on the surface of the condenser and evaporator to ensure good heat dissipation. For the humidification system, check the water level of the humidifier and whether the humidification pipe is unobstructed; for the dehumidification system, check whether the condenser tube is frozen and whether the drainage pipe is blocked. Repair or replace the faulty components in a timely manner.
(4) Control System Maintenance
If there is no problem with the hardware system, further inspection of the control system is needed. Contact the equipment manufacturer’s technical personnel to check through remote or on-site methods whether the components on the control circuit board are damaged and whether the control program has vulnerabilities or errors. For problems caused by improper operation, relearn the equipment operation specifications, set the parameters correctly, and avoid similar situations from happening again.
(5) Improving Environmental Conditions
Move the test chamber to a location with good ventilation, no direct sunlight, and away from heat sources and water sources. If the ambient humidity is high, place dehumidification equipment around the test chamber; when the ambient temperature is too high, install an air conditioner to regulate the room temperature. Ensure that the ambient temperature around the test chamber is within the equipment’s specified operating temperature range (generally 5℃ – 35℃) and the humidity does not exceed 85% RH.
IV. Prevention is Better than Cure: Daily Maintenance Tips
To reduce the frequency of temperature and humidity runaway, daily maintenance is crucial. Regularly (it is recommended once a month) clean the inside and outside of the test chamber, including the sensor surface, ventilation ports, condenser, and other parts; perform a comprehensive calibration and performance test on the equipment every 3 – 6 months; strictly follow the operating procedures when using the equipment, avoid frequently changing parameters and overloading operation. In addition, establish a device use and maintenance file to record each operation data, maintenance situation, and fault handling process, which is convenient for quick tracing and analyzing problems.
Temperature and humidity runaway in constant temperature and humidity test chambers is not an unsolvable problem. As long as the correct troubleshooting and solutions are mastered, combined with daily careful maintenance, the equipment can run stably and continuously, safeguarding scientific research and production. When encountering a runaway situation again, simply refer to the steps in this article to quickly restore the test chamber to “health.”