The high and low temperature alternating humidity test chamber is an important equipment for product development and quality inspection, and various malfunctions are inevitable during long-term operation. The following are typical fault phenomena, cause analysis, and targeted solutions for reference by operation and maintenance personnel:

1、 Excessive temperature deviation

Phenomenon characteristics

The deviation between the set temperature and the actual measured value exceeds ± 2 ℃, and the continuous fluctuation cannot be stabilized.

Core incentives

Inaccurate temperature sensor: Long term exposure of platinum resistors to high humidity environments leads to oxidation drift;

Air duct blockage: The sample placement in the studio is too dense, which hinders air circulation; Frost formation on the evaporator affects heat exchange efficiency;

Insufficient refrigerant: The slight leakage at the copper pipe welding point causes a lack of fluorine in the system, manifested as frequent low-pressure alarms.

Solution measures

Compare the sensor output values using a standard platinum resistance calibrator, and replace the sensor with a new one if the deviation exceeds the limit;

Clean the spacing between sample racks in the studio, regularly defrost and unclog the inlet filter of the centrifugal fan;

Fill an appropriate amount of R404A environmentally friendly refrigerant and use an electronic leak detector to check for leaks at pipeline solder joints.

2、 Abnormal humidity fluctuations

Phenomenon characteristics

The relative humidity display value fluctuates violently or never reaches the set lower humidity limit.

Key crux

Water level controller malfunction: The float valve is stuck, causing the water tank to not replenish water in a timely manner;

Humidifier tube blockage: water impurities deposit in the stainless steel pipes of the steam generator;

Drying filter failure: The molecular sieve in the regeneration tower saturates and loses its dehumidification ability.

Disposal Plan

Disassemble and clean the water level float assembly, and replace it with deionized water as the water source;

Blow the humidification pipeline in reverse with compressed air, and replace the 316L stainless steel humidification pipe if necessary;

Replace the dry filter element every quarter and perform a 96 hour continuous no-load dehumidification test after restarting.

3、 Frequent start stop of compressor

Abnormal performance

The compressor stops immediately after starting, accompanied by the tripping of the high-pressure switch.

root cause

Poor heat dissipation of condenser: Dust accumulation in the gaps between fins reduces heat transfer efficiency;

Capillary ice blockage: Excessive water content in the refrigerant forms ice crystals blocking the throttling device;

Voltage instability: The voltage fluctuation of the power grid exceeds the rated working range of the compressor motor.

Repair measures

Clean the condenser fins with a soft bristled brush every month and maintain a ventilation distance of ≥ 50cm;

Replace the molecular sieve drying filter, evacuate and refill with qualified refrigerant;

Install a voltage regulator module to ensure that the input voltage remains stable within the range of 380V ± 5%.

4、 Heating function failure

Fault characterization

The heating rate slows down significantly, and the highest temperature can only reach 80% of the set value.

Traceability analysis

Heating tube aging: Nickel chromium alloy heating wire burns out or magnesium oxide powder insulation layer breaks down;

Solid state relay damage: Contact adhesion causes the heating circuit to disconnect;

PID parameter drift: Temperature control instrument program disorder causes heating ratio imbalance.

Rectification methods

Use a multimeter to check the resistance of each heating tube and replace it with a spare heating tube of the same specification;

Replace Omron solid-state relay and check the contact status of the intermediate relay contacts;

Reset the PID parameters and shorten the integration time to 70% -80% of the original value.

Through systematic troubleshooting and periodic maintenance, the stability and service life of the test chamber can be significantly improved. When encountering complex faults, it is recommended to contact a professional maintenance team for in-depth diagnosis to avoid blind disassembly and secondary damage.