How to check the clogging state of the filters in my Sullair DHL-300?
- MMichael FuentesAug 12, 2025
To check the clogging state of the filters, read the differential pressure gauge installed on your Sullair Dehumidifier.

How to check the clogging state of the filters in my Sullair DHL-300?
To check the clogging state of the filters, read the differential pressure gauge installed on your Sullair Dehumidifier.
What to do if the alarm light is ON on my Sullair DHL-300?
If the alarm light is on, check the display to see if the filter needs replacement. If differential pressure switches are installed on the filters, replace the filter elements. If there are no switches, and it has been 6000 hours, replace the element. A high dew point alarm indicates that the dew point at the outlet exceeds 33 degrees F; in this case, refer to the troubleshooting steps for 'Moisture in the Outlet Air'. If an optional pressure switch in either the right or left tower has failed, identify the unpressurized tower via the screen, follow steps 2, 3, and 4, and replace the faulty pressure switch if necessary.
What to do if my Sullair Dehumidifier dryer towers do not switch correctly?
If the dryer towers on your Sullair Dehumidifier aren't switching correctly, the issue might stem from the solenoid valves PVA and/or PVB not activating. Refer to the specific troubleshooting steps for that problem. Alternatively, the inlet and/or outlet valve could be blocked, or the inlet solenoid might not be working; perform necessary maintenance. Also, inspect the purge exhaust mufflers for cleanliness and replace them if needed.
What to do if all the inlet air is discharged through the purge exhaust mufflers of my Sullair DHL-300?
If all the inlet air is being discharged through the purge exhaust mufflers of your Sullair Dehumidifier, it could be due to several reasons. First, the dryer may not be performing the switching cycles correctly, so refer to Step 2. The purge solenoid valve PVA and/or PVB might be blocked, requiring you to open and clean it. Another possibility is that the SHDC-2300 electronic controller is constantly supplying solenoid valve PVA and/or PVB; in this case, check the wiring and replace it if necessary. If the cycle times on the SHDC-2300 electronic controller have been changed, restore them to their original settings. Lastly, the regeneration nozzle could be clogged, so open and clean it.
Why are purge solenoid valves never activated in my Sullair DHL-300?
If the purge solenoid valves in your Sullair Dehumidifier are never activated, check the electrical supply or on/off switch for failures and verify the electrical wiring. The valve may also be blocked, requiring you to open and clean it. If the solenoid valve has failed, replace it.
What does it mean if there is liquid at the purge exhaust mufflers of my Sullair DHL-300 Dehumidifier?
If you notice liquid at the purge exhaust mufflers of your Sullair Dehumidifier, it indicates humidity in the outlet air. Refer to the troubleshooting steps for 'Moisture in the Outlet Air' to resolve the issue.
What causes Hi-Dew point in Sullair DHL-300 Dehumidifier and how to resolve it?
A high dew point in your Sullair Dehumidifier can be caused by several factors. It may indicate humidity at the dryer outlet, in which case you should refer to the troubleshooting steps for 'Moisture in the Outlet Air'. Ensure a constant airflow through the dew point measuring cell if the dew point meter has been changed. A blocked shuttle valve supplying air to the dew point meter should be cleaned to ensure dry air flows from the tower during drying. If the probe is broken, replace it. Air leaks in pipes or joints connecting the equipment should be verified and damaged parts replaced. Finally, a clogged pipe or joint connecting the equipment needs replacement.
| Brand | Sullair |
|---|---|
| Model | DHL-300 |
| Category | Dehumidifier |
| Language | English |
General safety information and regulations for operating the dryer.
Critical warnings regarding the operation and handling of the dryer.
Guidelines for the correct and intended use of the compressed air dryer.
Instructions for safe operation of pressure equipment.
Requirements for selecting a suitable installation location for the dryer.
Recommended piping and layout for dryer installation.
Specifies the required operating parameters for the dryer.
Instructions for connecting the dryer to the compressed air system.
Guidelines for connecting the dryer to the electrical power supply.
Checks and preparations before initial dryer operation.
Step-by-step procedure for the initial startup of the dryer.
Procedures for operating and safely shutting down the dryer.
Description of the control panel interface and its components.
Schedule and procedures for periodic dryer maintenance.
Procedures for performing maintenance and checks on the dryer.
Guidance on identifying and resolving common dryer problems.
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