Look to see where the refrigerant pipes enter the outside house wall and then go inside to see if the noise is coming from this area of the wall. If it is, you may have something in the refrigerant that shouldn't be there!

Yes, it comes from the wall near the outdoor condenser unit. It also makes the same noise in the bathroom ceiling near where the air handler is in the attic.

Is There Water in My Air Conditioning Unit?

https://www.cooling-heating.org/

Sound:

Dripping Water. If you hear the sound of dripping water coming from your indoor unit, it likely means condensation is not draining properly. Moisture naturally builds up in your HVAC system and should drain out if it’s working correctly. A blocked drainage tube could be preventing condensation from properly draining.

Sound:

A bubbling or gurgling water sound coming from your indoor AC or furnace unit is usually an indication of a pressure issue. Improper internal pressure could be due to an overcharge of refrigerant (too much). It could also be the result of a refrigerant leak. Anytime the refrigerant level is incorrect, it causes an imbalance of pressure and air can get in where it shouldn’t be, which in turn causes the bubbling or gurgling noise you are hearing.

Your air conditioner takes in warm air from your home and blows it over an evaporator coil which contains refrigerant. As the liquid circulates and absorbs heat, condensation will begin to form. If you’ve ever noticed water droplets on a cold glass during a hot summer day, you know what we’re talking about.

This moisture collects on your unit’s coils and runs down into the drain pan. Finally, the water flows through the condensation line which drains outside of your home. So, if your AC is working properly, this water should drain and not hang around in your unit, and you shouldn't hear any dripping noises.

When You Have a Problem

If you hear splashing around your house and it isn’t your kids playing in the pool, this is a sign that your air conditioner isn’t working properly. Some of the most common reasons your unit would be making a dripping noise include:

A clogged condensate drain line

A cracked drain pain

Improper installation or size of the unit

A broken condensate pump

A dirty air filter

Lack of refrigerant

"It lasts while the heat or air is running and stops when the unit cuts off"

Suggests its it not a leak but something to do with the refrigerant. Likely not something you can fix yourself.