Something is wrong: Your dehumidifier isn’t functioning properly, and you need to make the repair as quickly as possible.

But as mechanical devices, dehumidifiers contain complex inner workings with various components and parts. So what do you do, and how do you determine what’s causing the issue in the first place?

Here’s a quick guide for troubleshooting three of the most common dehumidifier issues.

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This guide will be useful assuming the dehumidifier was installed properly per the installation manual furnished and successfully met the initial startup procedure.

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How to troubleshoot common dehumidifier issues infographic

1. The dehumidifier will not operate at all

First check if the main power panel switch, to the dehumidifier, is in the ON position.  Confirm that the circuit breaker and/or fuse that serves the dehumidifier is not tripped or a fuse is not blown.

Confirm that the controls are on the ON position.  Verify that the humidistat is set between 50 and 60 percent relative humidity.  If the dehumidifier still does not operate call a competent HVAC servicer.


2. Humidity will not reach the set point

Assuming that the dehumidification system was effectively operating in the past look for these simple repairs:

  • If the blower in the dehumidifier is running it is possible that the compressor is not operating.  Check to see that the indicator light, on the dehumidifier, is confirming that the compressor is operating.
  • If the compressor is not running call a competent HVAC company for service. Using a separate calibrated hygrometer to determine the actual relative humidity in the pool room.
  • If it shows that the actual humidity is between 50 and 60 percent it is possible that the humidity sensor or the humidity control is defective. Verify that the pool water temperature is 2 degrees below the actual room temperature.
  • If the room temperature feels cool or is over 5 degrees below the water temperature it is possible that the room heating source is not operating.

3. The head pressure is too high

Assuming that the dehumidification system followed the proper start up procedure and met expectations previously the following may now be the cause.


  • The blower belt, in the dehumidifier may be worn or stretched or both.  Replace belt and tighten to the proper tension.
  • Check to see that the diffusers, on the registers for the dehumidified air, have not been obstructed or the dampers closed off inadvertently.  The return air filters in the dehumidifier are clogged and restricting air flow back to the dehumidifier.
  • Replace return air filters per the instruction manual.  If it is determined that the dehumidifier was operating with the return air filters removed, it is entirely possible that the condenser and/or the evaporator coil are plugged with debris restricting air flow.
  • If the dehumidifier is tripping the high head pressure switch during the cooling mode it is possible that the remote condenser coils are plugged with lint, grass or leaves restricting air flow or the blower belt (if applicable) needs attention.  Maintenance is critical for the successful operating of the dehumidifier and that also insures a long trouble free service life.

Topics: Dehumidifiers, Troubleshooting