Central air conditioners typically have removable filters that help clear particulates out of the incoming air so that you have the cleanest cool air inside your home. You do need to keep replacing and/or cleaning the filters periodically to make sure your system runs efficiently. If you go to change the filter and see signs of current moisture or water stains from past moisture, you need to determine the cause as soon as possible.

There are a few potential causes of moisture on your central air conditioner's air filter. You can perform most of the checks yourself, though you might need an HVAC technician's help to actually fix the problem.  

Overly Humid Air

Humid summer air comes through your air conditioning system and can leave behind some of that excess moisture. If you live in an area with frequent humidity, you will want to install a dehumidifier to stop the moisture buildups, which can damage the machinery of your air conditioner over time.

Does your home already have a dehumidifier? Call in an HVAC technician to service the unit to make sure a setting wasn't accidentally changed or that the unit isn't going out.

Clogged Coil Drain

Consult your owner's manual to determine the location of your air filter in relation to the evaporator coils, which are found inside the air handler that is usually part of your furnace. If the air filter is close to the coils, the moisture could be coming from the condensation naturally created by the evaporator coils.

Evaporator coils take in liquid refrigerant that fuels the cooling system and change that refrigerant into a gas. The change causes the exterior of the coils to become cold, which provides the cooling source for warm air blown across the coils via motorized fan. Condensation forms on the cooled coils and drips down into the bottom pan to be carried straight into a drain pipe through either gravity or a condensate pump.

If the drain pipe becomes clogged, the water in the pan can overflow and, depending on the location of your air filter, end up moistening the filter. A clear sign that this is the problem is that there is moisture on the floor around your furnace along with the moistened filter.

You can try to unclog the drain using a commercial drain cleaner. If you suspect a broken condensate pump is the issue, call in an air conditioning repair tech for a replacement.

Dirty or Eroded Coils

Does the drain seem to be working properly but you still have excess water? The coils could be producing extra condensate due to dirt buildup on the surface or erosion caused by time and gradual water damage.

You can inspect the surface of the coils after turning off all electricity to the unit. If dirt alone is the issue, use a commercial, no-rinse, foaming coil cleanser to take care of the problem. Spot some erosion or other physical signs of wear? Call in an HVAC technician for a new set of coils.

For more information about possible causes of moisture in your HVAC unit, contact a company like Pristine Air Conditioning Corp.