What to Do When Your Bathroom Fan Isn’t Removing Moisture

A bathroom exhaust fan is supposed to be your first line of defense against moisture buildup, mold, and stale air. It quietly whisks away moisture and odors, keeping your bathroom clean, dry, and free of mold. But what happens when it stops doing its job, when your bathroom mirror stays fogged up, or worse, you start noticing peeling paint or mildew creeping in?

If your bathroom fan isn’t removing moisture like it used to, you’re not alone. It’s a common issue, and luckily, most of the time it’s something you can fix yourself. In this article, we’ll walk you through why your bathroom fan may not be working properly and what you can do about it, step by step.

The information in this article may not apply to your specific appliance model. We recommend consulting your manufacturer’s documentation or contact us with any questions.

Why Bathroom Ventilation Matters

Before diving into fixes, it’s important to understand why your bathroom fan is so critical. Bathrooms generate a lot of moisture, showers, baths, and even hand washing all add humidity to the air. Without proper ventilation:

• Mold and mildew can grow.
• Paint and wallpaper may peel.
• Wood trim and doors may warp.
• Air quality suffers.

A well-functioning exhaust fan removes this humid air, helping your bathroom, and your entire home, stay in good condition.

Signs Your Fan Isn’t Working Effectively

How can you tell your fan’s not doing its job? Look out for:

• Foggy mirrors that take a long time to clear
• Persistent humidity even after the fan runs
• Visible mold or mildew, especially on ceilings or in corners
• Peeling paint or wallpaper
• Strange noises from the fan or no noise at all
• Odors that linger longer than they should

If you’re seeing any of these signs, your fan may be underperforming, or not functioning at all.

Start with the Basics: Clean the Fan

Dust, lint, and bathroom grime can build up on your fan blades and grill, reducing its effectiveness dramatically.

1. Turn off power at the breaker to be safe.
2. Remove the fan cover, usually it pops off or has a couple of spring clips.
3. Use a vacuum with a brush attachment to remove dust from the fan blades, motor, and housing.
4. Wipe down the cover and any visible components with a damp cloth.
5. Reassemble and restore power.

Regular cleaning, about once or twice a year, can go a long way in keeping your fan efficient.

Check the Vent Path

Even if the fan itself is working, blocked or damaged ductwork can prevent moisture from being expelled properly.

Things to Inspect:

• Flexible ducts that have sagged or collapsed
• Rigid ducts that are disconnected
• Exterior vent flaps that are stuck closed or clogged with debris

Follow the ducting (if accessible) from the fan to the exterior of your home. If airflow feels weak at the exit point or you notice blockage, clear it or repair as needed.

Test Airflow with a Simple Trick

Not sure if your fan is actually pulling air? Try this:

1. Turn on the fan.
2. Hold a single sheet of toilet paper or tissue up to the grille.
3. If the fan grabs and holds the tissue in place, it’s pulling air.
4. If the tissue falls away, you’ve got a suction problem.

This test isn’t scientific, but it’s quick and can point you toward a problem with airflow.

Consider the Fan’s Capacity

Even a clean, working fan might be underpowered for your bathroom size. Fans are rated in CFM (cubic feet per minute). A basic rule of thumb is:

• 1 CFM per square foot of floor space for bathrooms up to 100 square feet
• For larger bathrooms or those with multiple fixtures (e.g., a tub and separate shower), you’ll want more.

If your bathroom is 80 square feet, your fan should be at least 80 CFM. Undersized fans just can’t keep up with moisture.

Evaluate the Run Time

Even the best fan won’t help much if it’s not on long enough.

• Run the fan during your shower and for at least 20 minutes afterward.
• Consider installing a timer switch so the fan runs for a full cycle even after you leave the room.

If your current fan shuts off too soon (especially with a standard wall switch), upgrading the control can improve moisture management significantly.

Listen for Electrical Issues

If your fan isn’t turning on at all, or runs intermittently, electrical problems could be to blame.

• Wall switch: Try replacing it if it feels loose or unresponsive.
• Wiring connections: With power off at the breaker, inspect for loose or burnt wires.
• Motor burnout: If the fan hums but doesn’t spin, the motor might be bad.

Replace an Outdated or Worn-Out Fan

Sometimes the fan is simply too old or broken to perform well anymore. Signs you need a new fan:

• It’s more than 10–15 years old
• It’s excessively noisy, even after cleaning
• It doesn’t improve humidity levels despite all efforts

Fortunately, modern fans are quieter, more efficient, and easier to install than ever before. Look for one with the correct CFM rating, low sone (noise) levels, and Energy Star certification.

If you’re upgrading, consider a smart feature: a humidity-sensing fan. These units turn on automatically when humidity rises, ensuring proper ventilation whether you remember or not. They’re ideal for families, guests, and anyone who tends to forget to flip the fan switch.

Where To Find Us 

If you need any replacement parts for your appliances, you can enter your model number at AppliancePartsPros.com to locate and order them quickly. Most orders arrive in just two business days, and we have tons of great information in our repair help section and YouTube videos to help you troubleshoot.

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