1. Dehumidifier Quickly Shuts Down After Startup, Long Restart Interval, Poor Dehumidification EffectFault Phenomenon: The dehumidifier automatically shuts down shortly after startup and requires a long wait before it can be restarted again, with significantly reduced dehumidification effectiveness.

Inspection Steps:

  • Measured outlet air speed is notably lower than normal.

  • Used a multimeter to detect the resistance between the fan motor leads, finding it much lower than the standard value.

Repair Measures: Replaced the faulty fan motor, resolving the issue.

Cause Analysis: The winding coils of the fan motor have a short circuit, causing the fan speed to decrease and air volume to diminish. Reduced air volume results in less air flowing through the condenser, increasing the compressor's discharge pressure and triggering an overheat protection shutdown. The compressor requires extended cooling before it can restart.

  2. Dehumidification Effect Decreases After Period of UseFault Phenomenon: A dehumidifier, after more than a year of use and a prior repair, shows normal compressor and fan operation but extremely poor dehumidification effect when used again after a period of inactivity, with little to no water condensation in an environment with 83% relative humidity and 12°C temperature.

Inspection Steps:

  • Air filter screen and evaporator, condenser surfaces are clean.

  • No oil leakage signs on pipe surfaces.

  • Frost appears briefly near the capillary tube at the evaporator, followed by shutdown. After some time, the frost melts, and the compressor can restart.

  • Wrapping the capillary tube and evaporator interface with a hot towel restores normal dehumidification, indicating ice blockage in the refrigeration system.

Repair Measures: Removed refrigerant containing excessive moisture from the system, purged the system with 0.3 MPa nitrogen, evacuated it using a vacuum pump for 20 minutes, and added the specified amount of refrigerant. After 30 minutes of refrigeration operation, evacuated again for 30 minutes or longer, ensuring the vacuum level met requirements before charging the exact amount of refrigerant, restoring normal operation.

Cause Analysis: During maintenance, moisture may have entered the system or refrigerant with high moisture content was added. Moisture freezes at the capillary tube and evaporator interface due to refrigerant throttling and temperature reduction. Gradually, ice accumulates and blocks the capillary tube, preventing refrigerant flow and dehumidification function. The compressor shuts down due to protective mechanisms, and heating the capillary tube melts the ice crystals, allowing the compressor to resume operation, but with significantly reduced dehumidification effectiveness.

  3. Increased Noise and Reduced Dehumidification Effect After Dehumidifier RepairFault Phenomenon: After dehumidifier repair, noise significantly increases, accompanied by decreased dehumidification effectiveness.

Inspection Steps:

  • The dehumidifier structure is stable and placed securely.

  • Noise mainly originates from the compressor.

  • Evaporator appearance is normal, with no frosting.

  • Excessive frosting on the suction line indicates excessive refrigerant charging.

Repair Measures: Appropriately discharging some refrigerant restored normal dehumidifier operation.

Cause Analysis: During repair, refrigerant was not charged according to standards, with excessive charging leading to liquid slugging, which increased compressor noise. Liquid droplets in the suction gas continue to evaporate within the suction line, causing frosting on its surface.

Dorosin has been deeply rooted in the dehumidification industry for two decades, specializing in providing comprehensive temperature control solutions. For more information, please stay tuned for our follow-up reports. Stay tuned for the next installment.