my dehumidifier is freezing up, there's ice all over the coils inside, what causes that?

Diagnosis

The freezing of the evaporator coils in the Frigidaire FFAD2233W1 occurs when the refrigerant temperature drops below the freezing point of water, causing moisture in the air to crystallize on the fins rather than condensing into droplets. This is almost always caused by a lack of sufficient airflow across the coils. When the fan cannot pull enough warm ambient air over the aluminum fins, the heat exchange process fails, and the coil temperature plummets, leading to a rapid buildup of ice. You can confirm this by checking the air filter and the intake vents. If you notice a significant drop in air velocity at the exhaust vent or if the foam filter is clogged with gray dust and pet hair, the airflow is restricted. Additionally, this model is not designed for low-temperature environments; if the room temperature drops below 60°F (15°C), the unit will naturally struggle to maintain a temperature above freezing, leading to "frosting" even if the filters are clean. In rare cases, a refrigerant leak (low Freon) can cause a localized drop in pressure, which lowers the boiling point of the refrigerant and causes ice to form specifically at the entry point of the evaporator coil.

How to Fix It

To resolve the icing issue and restore the unit to operational status, follow these precise steps:

1. Complete Power Down: Immediately unplug the unit from the wall outlet. Do not simply turn it off via the control panel. The compressor must stop completely to prevent further ice accumulation.
2. Manual Defrost: Do not attempt to scrape the ice with a knife or screwdriver, as the aluminum fins are fragile and a puncture will leak all refrigerant. Allow the unit to sit in a room at 70°F for 24 hours until all ice has melted into the bucket. If you are in a rush, use a hairdryer on a "Low/Cool" setting from 12 inches away.
3. Filter Deep Clean: Remove the foam air filter located behind the front intake grille. Wash it with warm soapy water and a soft brush. Squeeze it gently to remove debris. Ensure the filter is 100% dry before re-inserting it; a damp filter restricts airflow even more than a dirty one.
4. Coil Inspection: Use a vacuum with a soft brush attachment to gently remove any dust buildup from the remaining visible areas of the evaporator coils.
5. Environmental Adjustment: Ensure the unit is placed at least 12 to 18 inches away from walls, curtains, or furniture. This ensures the 360-degree airflow required for the FFAD2233W1 to operate without freezing.
6. Restart and Monitor: Plug the unit back in and set the humidity target to "Continuous" (CO) for one hour to verify that the coils are shedding water normally into the bucket without frosting.

If That Didn't Work

• Check the Fan Motor: If the fan is spinning slower than usual or making a humming sound, the motor capacitor may be failing. If the fan doesn't move enough air, the coils will freeze regardless of how clean the filter is. Listen for a "clicking" sound which indicates the motor is struggling to start.
• Verify Thermistor Function: The FFAD2233W1 uses a defrost sensor (thermistor) to tell the compressor to shut off when ice begins to form. If this sensor is displaced or faulty, the compressor will run indefinitely, ignoring the ice buildup. A technician can test this sensor for resistance using a multimeter.
• Refrigerant Leak Test: If ice forms in a specific "ball" or patch at the top of the coil while the rest of the coil remains warm, you likely have a slow refrigerant leak. This creates a pressure drop that freezes the coil. Since this is a sealed system, this requires a professional HVAC technician to solder the leak and recharge the gas.
• Relocate to a Warmer Zone: If you are using this in a garage or basement where the temperature is consistently below 60°F, this model will continue to freeze. You will need to move the unit to a warmer room or upgrade to a "Low Temperature" specific dehumidifier designed for garage use.

Heads Up

• Filter Frequency: Clean the foam filter every 2 weeks during peak summer humidity to prevent the airflow restriction that leads to coil icing.
• Avoid "Continuous" Mode in Cold Rooms: Using the "CO" (Continuous) setting in a room below 65°F removes the humidity-based shut-off, which significantly increases the risk of freezing the coils.
• Bucket Maintenance: Ensure the bucket is seated perfectly. If the bucket is slightly skewed, the float switch may malfunction, causing the unit to run longer than necessary, which can contribute to frosting.
• Storage Tip: When storing the unit for winter, drain the reservoir completely and wipe the coils dry to prevent permanent corrosion or mold growth on the fins.