Unlike a clogged air filter that happens quite commonly in many HVAC systems, a wet air filter can be a cause of concern for homeowners and could be a sign that something within your HVAC system needs to be fixed.
One likely cause of a wet filter in an HVAC system is a condensation leak. This happens when debris, dust, and dirt clog the drain line. When this happens, the moisture that has liquidised backs up in the drip pan since its normal route is blocked. This then leads to water overflowing and soaking the air filter.
Another reason could be old age of your HVAC system which is liked to a damaged drain pan. In this case, the pan needs to be replaced. It could also be caused by a dirty air filter that causes a blocked airflow which then causes the evaporator coil to freeze and melt. When the melted water is too much for the drain pan, it could cause a wet filter in your HVAC system.
There are many potential causes and the best way to find out why is to hire WeAreChoice.co.uk, an air conditioning company in Surrey, to check your unit.