Posted on: 23 November 2020
Your air conditioner's filter should never be damp when your unit is operating properly, so a wet air filter is a sign that there's a problem with your air conditioning system. It's a fairly serious problem as well—if you don't fix it, it's very likely that mold will begin growing in your air handler. Your indoor air quality will significantly decline and you'll begin to smell mildew all throughout your home. To find out what could be causing your air filter to get wet and how you can fix it, read on.
Clogged Condensate Line
The most common cause of a wet air filter is a clog in the condensate line. Condensation will collect on the evaporator coil in your air handler while your air conditioning system is running. It slowly drips down into the condensate pan located underneath the coil, then drains into the condensate line leading towards a floor drain or outside of your home. If the condensate line is clogged, the condensate pan will eventually overflow and soak your air filter.
Condensate lines commonly become clogged due to a combination of dust and a bio-mat that's formed by bacteria. You can remove the clog using a pipe snake or by suctioning it out using a wet/dry vacuum attached to the end of the condensate line. In order to prevent clogs from forming in the future, periodically add biocidal tablets to the condensate pan to inhibit bacterial growth.
Evaporator Coil Freezing Over
If your evaporator coil freezes over, it will produce a considerable amount of water vapor when it begins to melt. The water vapor will be blown towards your air filter, causing it to become damp.
A freezing evaporator coil is most often caused by low refrigerant levels inside your air conditioning system. Air conditioners work by forcing liquid refrigerant to expand into a gas. When refrigerant levels are low, the refrigerant is able to expand more quickly than it's designed to, causing the evaporator coil to become freezing cold. In order to fix the problem, you'll need to call an air conditioning repair service. They'll stop the leak and recharge your air conditioner with refrigerant.
An evaporator coil can also freeze due to low airflow. It's designed to absorb heat from the air that's flowing over it. If not enough air is moving through your air handler, the coil becomes too cold and freezes over. Low airflow is usually caused by installing the wrong type of air filter. If your filter is too thick, it reduces the amount of air moving through your air handler. Low airflow can also occur if you have a belt-driven blower fan that's nearing failure. The belt can begin to slip while the motor's running, resulting in a very low fan speed. You'll need to call an air conditioning repair service and have them replace the blower fan in order to solve your airflow problem.
Missing or Dry P-Trap in Your Condensate Line
If you have a negative pressure air handler in your air conditioning system, you'll need a working P-trap in your condensate line. Negative pressure air handlers draw air over the evaporator coil rather than blowing air directly over it. However, this system would also suck air upwards through the condensate line. When air is sucked into the air handler through the condensate line, it turns the condensate into a mist that will spray all over the inside of the air handler, including on your air filter.
In order to prevent this, a P-trap is installed in the condensate line. It fills with condensate in order to provide a barrier between the air in the air handler and the air outside your home, which prevents suction from occurring.
When you don't use your air conditioner for several months, the water in the P-trap may dry out. You can refill it by pouring a few cups of water into your condensate pan, restoring the barrier and allowing the P-trap to function again.
If your air conditioner wasn't installed correctly, you may be missing a P-trap entirely. It looks like a small U-shaped dip in your condensate line, and it's usually located right next to your condensate pan. If you have a negative pressure air handler (which places the fan in front of the evaporator coil rather than behind it), you'll need to have one installed by an air conditioning repair technician.
To sum it up, your wet air filter is most likely caused by a clog in your condensate line. Improper installation, a dry P-trap, or your evaporator coil freezing over are all fairly rare in comparison. If unclogging your condensate line doesn't solve the problem, schedule an appointment with an air conditioner repair company as soon as possible—if the cause of your wet air filter isn't fixed, you're likely to end up with mold in your air handler.Share