The dehumidifier fan blade may be damaged or incorrectly installed. Manually rotate the blade to check that it spins freely without contacting the housing. If the blade does not turn smoothly or rubs against the housing, it needs replacement. Also wiggle the motor shaft to check if it is loose, indicating the blade is not properly attached. If tightening the set screw does not secure the fan blade, it requires replacement.
To diagnose a dehumidifier fan that is not operating, first manually rotate the fan blade to confirm it spins freely without contacting the housing. If the blade is obstructed and cannot turn smoothly or rubs against the housing, it requires repair or replacement. Next use a multimeter to check if the fan motor is receiving electrical power. If the motor is getting power but the fan still does not run, this indicates the motor itself is defective and should be replaced.
The dehumidifier shuts off when the water bucket gets full and the bucket switch opens. A defective, stuck open bucket switch will stop the dehumidifier from operating. Use a multimeter to check the bucket switch for continuity to determine if it is faulty. If the multimeter test shows the bucket switch does not have continuity, the switch needs to be replaced. This will allow the dehumidifier to function properly by turning on and off based on the water bucket level rather than staying off due to a faulty bucket switch.
Manually rotate the blower wheel to diagnose operation issues. If the wheel does not spin freely or rubs against the housing, it needs replacement. Also check if the wheel wobbles while turning, indicating it is loosely attached to the motor shaft. In that case, tighten the blower wheel if possible or replace it if the issue persists. Visually inspect the wheel as well and replace it if there is any physical damage causing obstructions to air flow. Following these steps to identify damage, obstructions, or loose mounting will determine if the blower wheel requires repair or replacement to properly circulate air again.
The humidity sensor tracks the moisture levels in the air. If the humidity becomes too elevated, contacts within the humidity sensor close to signal the dehumidifier to turn on. A malfunctioning humidity sensor will stop the dehumidifier from operating even at high humidity levels. To diagnose, check that the humidity sensor contacts are closing properly when humidity is high. If the contacts are closing but the dehumidifier does not run, the humidity sensor itself is likely faulty and requires replacement.
The humidistat tracks the humidity in the air. If the humidity is high, the contacts in the humidistat close to turn on the dehumidifier. Faulty humidistat contacts that fail to close will prevent the dehumidifier from operating. Use a multimeter to check the humidistat for continuity to test if it is defective. If the multimeter test shows the humidistat does not have continuity, the contacts are not closing properly and the humidistat needs replacement. Replacing a faulty humidistat allows the dehumidifier to function by powering on when humidity levels are too high.
The compressor pumps and compresses the refrigerant through the evaporator and condenser coils in the dehumidifier. If the compressor fails, the dehumidifier cannot cool properly. But a faulty compressor is uncommon. First, check the more frequently defective parts before replacing the compressor. If all other components test functional, use a multimeter to check the compressor for continuity. If the multimeter test indicates no continuity in the compressor, it needs to be replaced. Because replacing the compressor requires an EPA certified technician, it is typically more cost-effective to replace the whole dehumidifier unit rather than just the compressor.
The control board tracks the moisture levels in the air. If the humidity gets too high, contacts in the humidistat close which signals the control board to turn on the dehumidifier. A defective control board will prevent the dehumidifier from running even when the humidistat contacts are closed due to high humidity. To test if the control board is faulty, check that the humidistat contacts are closing properly. If the humidistat contacts are closing but the dehumidifier does not run, the control board is likely defective and needs to be replaced.
The electrical outlet may have lost power. To check, plug a working electrical device into the outlet to see if it turns on. If the test device does not power on, the outlet is not getting electricity. This indicates an issue with the outlet's circuit rather than the dehumidifier. Check the circuit breakers and fuses to diagnose where the power loss occurred. Resetting tripped breakers or replacing blown fuses will restore electricity to the outlet.