Troubleshooting Diagnostic Codes

When the dehumidifier is turned ON, the display will show a diagnostic code along with "SERVICE REQUIRED." If multiple codes are detected, they will be displayed consecutively.

Diagnostic Codes and Solutions

Code E1 – Internal RH/Temperature Sensor Open or Shorted

Issue: The User Interface Assembly is not receiving a proper signal from the temperature/RH sensor.

Solution:

1. Turn off power using the ON/OFF toggle switch.

2. Remove the User Interface Assembly by unscrewing the four screws securing it to the housing.

3. Carefully disconnect the three-wire cable at the back.

4. Check the connection between the sensor board and the control board.

5. If the connection is secure but the problem persists, replace the RH Sensor Board (5460).

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Code E2 – High Refrigeration Pressure

Issue: The discharge line temperature exceeds 190°F. This typically occurs due to high inlet air temperature (>100°F) or low airflow.

Solution:

1. Turn OFF the ON/OFF toggle switch to reset the code.

2. If the fan is not working, see the "Fan Does Not Function" section (page 15).

3. Ensure the backflow damper moves freely and the ductwork is unobstructed.

4. If ducted to an HVAC system, verify that the inlet is not connected to the HVAC supply side.

5. For attic installations, inspect for duct leaks if ambient temperatures are high.

6. For ventilation applications, mix indoor air with incoming air to moderate temperature.

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Code E3 – Model 76 Remote Control Communication Loss

Issue: A Model 76 control connected to the Remote terminals has lost communication.

Solution:

1. Verify correct wiring to terminals A, B, +, and - on both the Model 76 and User Interface Assembly.

2. Ensure terminal screws are tight.

3. Remove the Remote terminal block and measure DC voltage across the + and - pins (should be ~35V DC ±3V).

4. If voltage is 0V, replace the User Interface Assembly (5445).

5. If wiring is correct and the issue persists, reconnect the Model 76 using a short test wire. If E3 disappears, replace the original wire; otherwise, replace the Model 76.

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Code E4 – Insufficient Capacity

Issue: The suction line temperature has not dropped at least 5°F within 20 minutes after compressor startup.

Solution:

1. Turn OFF the dehumidifier using the ON/OFF button.

2. Restart and enter Installer Test Mode:

   • The fan runs for 3 minutes (display: "AIR SAMPLING").

   • Then, "DEHUMIDIFYING" appears, and the compressor starts.

   • If the compressor does not start, check for electrical issues (see step 4).

3. If the compressor starts, verify the refrigeration system operation.

4. If the compressor fails to start:

   • Turn OFF power and access the electrical components.

   • Check wire connections to the Internal Control Board and run capacitor.

   • Test the run capacitor (should be 45 ±5% microfarads).

   • If voltage at compressor terminals is 120V AC but the compressor does not run, inspect the run capacitor or compressor overload switch.

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Code E5 or E6 – Temperature Thermistor Failure

Issue: The High (E5) or Low (E6) Temperature Sensor signal is open or shorted.

Solution:

1. Turn OFF power and remove the side panel.

2. Disconnect and test the sensor resistance (refer to the temperature resistance table in the manual).

3. Reconnect the sensor and turn power back ON to reset the code.

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Code E7 – Float Switch Open

Issue: The Float Switch input is open, indicating possible water buildup in the drain pan or a faulty switch.

Solution:

1. Allow the unit to self-correct.

2. Drain any water from the secondary drain pan.

3. Inspect the Float Switch wiring and ensure proper seating.

4. If a jumper is installed, reseat it securely.

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Code E8 – Inlet Air Temperature/Dew Point Out of Range

Issue: The inlet air temperature is <50°F or >104°F, or the dew point is <40°F.

Solution:

1. Turn OFF the toggle switch to reset the code.

2. Verify proper ducting:

   • Do not connect inlet ducting to the HVAC supply side.

   • Check for duct leaks in attic installations.

   • Adjust ventilation settings to mix indoor air with the incoming air.

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Code E9 – Outdoor Temperature Sensor Open or Shorted

Issue: The Outdoor Temperature Sensor signal is out of range. This occurs only if the ventilation feature is enabled.

Solution:

1. Remove the User Interface wiring access cover.

2. Test the sensor resistance (refer to temperature resistance table in manual).

3. If the sensor is faulty, replace it (8052).

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Other Common Issues

Water Leaks

Solution:

1. Ensure the unit is level.

2. Clean or replace drain tubing; ensure a continuous downward slope.

3. Pour water into the drain pan to check for leaks.

4. Plug or elevate the drain tube and observe for 15-20 minutes.

5. If leaks persist, inspect the drain pan and tube for damage.

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Fan Does Not Function

Solution:

1. Ensure the power outlet is live.

2. Verify electrical connections.

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Circuit Breaker Trips

Solution:

1. Ensure the unit is plugged into a 15A circuit.

2. If other high-power devices share the circuit, consider a dedicated line.

3. If the circuit is sound:

   • Inspect wiring at the power switch and control board.

   • Test the run capacitor (should be 45±5% µF).

This troubleshooting guide should help diagnose and resolve most issues encountered with the dehumidifier.