3 Reasons Your Air Conditioner Filter Is Wet and How to Fix It

When it comes to AC filters, dry is best

Man removing ceiling air filter
Photo: Serenethos / iStock / Getty Images Plus / Getty Images
Man removing ceiling air filter
Photo: Serenethos / iStock / Getty Images Plus / Getty Images
Highlights
  • Leaky drain pans are a common reason for soggy AC filters.

  • A blocked condensate line or frozen evaporator coil could also be to blame.

  • Wet filters can lead to HVAC damage and mold, so it’s important to replace them.

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If your air conditioner filter is wet, it’s a sign that something isn’t quite right. Fortunately, though, it doesn’t always mean that there’s something seriously wrong with your HVAC system. In fact, the fixes are often fairly easy (and DIY-friendly). But first, let’s answer the question at hand: Why is your air conditioner filter wet? Here are three potential causes, as well as next steps for addressing each one.

What Happens if Your AC Filter Gets Wet?

It’s natural for your air conditioner to produce condensation, but that moisture shouldn’t reach your filter. Soggy filters can reduce airflow and make your HVAC system work harder, meaning that your AC will use more energy (and your utility bills will be higher). 

On top of that, a wet filter can put added strain on other parts of your HVAC system and potentially cause it to break down. Plus, damp filters can lead to mold in your air conditioner. When mold circulates in your air ducts, it can result in health problems like headaches, fatigue, nausea, and allergy-like symptoms.

1. Leaky Drain Pan

As your air conditioner runs, it creates condensation as part of the cooling process. This condensation collects in the drain pan (also known as a drip pan), which sits beneath the evaporator coils. Eventually, the condensation leaves your HVAC system through a condensate drain line. Over time, the pan can develop cracks, holes, or rust. As a result, water can leak onto your AC filter. 

How to Fix It

If you’re comfortable poking around your air conditioner, you can open it up and look for signs of wear and tear on your drain pan. (It should be near the bottom of your indoor unit, connected to the drain line.) If you see signs of damage, you may need to replace the pan. In that case, you should call a local AC repair company.

2. Clogged Condensate Drain Line

Air conditioning units outside
Photo: Maudib / iStock / Getty Images Plus / Getty Images

Another common culprit of a wet AC filter is a blocked condensate line. Ideally, this part of your HVAC system is supposed to remove condensation after it collects in the drain pan. But if debris—like dirt, pet hair, or mildew—gets into the line, it can back up into the drain pan. At that point, the water has nowhere left to go and can spill onto your filter or other parts of your air conditioner.

How to Fix It

Fortunately, cleaning a clogged condensate line is a simple DIY project. After turning off the AC, find the condensate line and access point, flush the system with distilled vinegar, and follow the vinegar up with a water rinse.

3. Frozen Evaporator Coil

Evaporator coils contain refrigerant and work together with condenser coils to produce the cool air that comes out of your AC. However, there are situations where the refrigerant can get too cold (often due to insufficient airflow from a dirty air filter) and freeze the evaporator coils. When they thaw, the condensation can drip onto your filter and make it soggy.

How to Fix It

Sometimes, a frozen AC unit will fix itself, but you shouldn’t count on it. Instead, it’s better to unfreeze the air conditioner yourself or hire an HVAC expert to do it. If you decide to DIY it, you’ll start by turning off the AC and starting the fan to begin the thawing process. Then, you should replace the filter and clean the coils (if they’re dirty).

How to Prevent Your AC Filter From Getting Wet

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While you might not be able to prevent a drain pan from rusting over time, there are other steps you can take to reduce your future risk of wet filters. These include: 

Frequently Asked Questions

Don’t run your AC with a wet filter. It can cause your AC to work too hard, which will run up your utility bill and cause extra wear and tear on the system. You could also spread moisture and mold throughout your house. Turn off the AC, remove the wet filter, and check for cracks or clogs. Fix the problem (with a pro’s help, if you need it), and put a dry filter in place before you turn the system back on.

It’s never a good idea to run your AC without a filter, even just for a night. The filter defends your HVAC system from the dust, dirt, debris, and other grime in your home. Without a filter, those contaminants are more likely to get inside your system and potentially damage it. 

If you run an AC with a dirty filter, it could allow dust and dirt to build up in your ductwork, which could make you sick. At the same time, your air conditioner won’t work as efficiently as it would with a clean filter, likely resulting in less airflow, more wear and tear on your HVAC system, and higher energy bills.

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