Air Conditioning - water ponds under a\c

water pond under central a\c unit.
any idea what might cause this?
unit is five years old.

I assume you are talking about the air handling unit? Is it in you basement or under the house? Need a little more info here please.

hello,
yes is the air handle unit inside the house.
it work fine until 3 days ago.
the drain line is clear, the water drains fine but there is still water ponding under the unit.

If the drain line is clear I dont know of where it would come from unless condensation on the outside of the unit is causing it.

Do you have a new puppy in the house? Other than that you may find that your coil is freezing and when it thaws out there is more wtaer than the drain can handle and it overflows the evap drain pan and runs onto the floor PUDDLING. Make sure your filter is clean (low airflow causes frozen coils) and all supply ducts are open and not restricted and that the blower motor is not cutting off while the condensor (compressor) is running. If it is still freezing after you have done the basic checks then you will have to have the refrigerant level checked by a pro.

Open the Air handler, turn on the system and you should be able to see where the leak is.