Coils icing up even though your unit is supposed to defrost itself? The frost sensor tells the dehumidifier when to pause and melt ice off the coils. When it fails, the unit either freezes over or defrosts too often.
Here is how the frost sensor works and how to fix it.
This article will teach you:
- What the frost sensor does
- Why it fails
- What to check first
- When it has failed
Why the Frost Sensor Fails
- A loose sensor not touching the coil.
- Dust insulating the sensor.
- Low airflow overwhelming the defrost cycle.
- A worn sensor.
What You’ll Need
- A soft brush
- Your owner’s manual
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How to Fix the Frost Sensor
- Defrost fully. Turn the unit off and let all ice melt.
- Check the sensor. Confirm the frost sensor sits against the coil, not loose.
- Clean around it. Dust the sensor and coil area.
- Improve airflow. Clean the filter so warm air reaches the coil during defrost.
Pro Tip: The frost sensor has to physically touch the coil to read its temperature. If it has slipped out of position, it cannot trigger the defrost cycle, and the coils ice over.
Didn't fix it? Ask a technician on the AppliancePartsPros forum.
Post your model number, the symptom, and what you've already tried. Appliance techs and experienced DIYers answer for free, usually the same day.
Ask the forum →80,000+ solved repair threads · no account needed to readWhen to Look a Little Deeper
Because frost control ties to icing, it helps to check related parts, and reviewing freezing coils, the humidity sensor, or a fan that will not run can reveal the cause.
Because prevention matters, understanding why a dehumidifier freezes up and how to prevent it and fixing a unit not detecting humidity changes both help.
When to Call a Pro
If the sensor is seated and clean and airflow is good but the coils still ice up or defrost oddly, the sensor or control board has failed and needs service.
Related guides
- Simple Steps to Fix the GE Air Conditioner F4 Error
- Portable Air Coolers: Tips for Increased Effectiveness
Wrapping Up
Frost sensor trouble shows up as icing. Here’s the recap:
- Defrost the unit fully.
- Confirm the sensor touches the coil.
- Clean the sensor and coil area.
- Improve airflow with a clean filter.
Reseat and clean the sensor, and defrost works again. You’ve got this.
Once you know which part failed, find the matching dehumidifier parts by model number so the replacement fits the first time.
Still stuck after this guide?
Two free options: post your model number and symptom on the forum, or search the model number in the shop to see every part that fits.
