There are only a couple ways to get air in the water line, coming from the well. The most common is a hole, or leak in a fitting, or the suction line if it is an above ground pump. if it is a submersible then the same situation only the hole or leak would be in the pipe coming out of the pump to supply water to the user. Both of these have to be resolved by pulling pipe and replacing or repairing it.
The second most common is a hole in the well casing or the water level drops below the pick up do to low water volume, over pumping of the well.
Got to be a pin hole in the line somewhere.
Yes
A clogged air conditioner drain line can cause water leakage.
If everything is functioning as it should the pump should push all the air out of the system. If there is consistently air in the system it is probably seeping in on the suction side of your pump, which will shorten the life of your pump. Check your suction line for leaks.
somehow you'll hear a windy noise in the water line
Install an automatic air vent on the line
In a well system, water is propelled by air pressure.
air in a boier system: noise, possible no/ low heat in certain areas. usually means system needs to be bled / pressure checked. air in a potable sytem: cracked line in well above water level. recent plumbing service. gasses present in well water.
Having air in the water line can lead to reduced water pressure, sputtering or spurting water from faucets, and potential damage to water-using appliances. It can also indicate a leak in the system or a problem with the water supply.
To release air that cause water hammer
Unless an air-dryer is installed, condensation will occur in air line. Drain condensation out of compressor daily.
Filling a spa or pool with a water softener will not cause you to have air in the plumbing. Air in your plumbing can be trapped regardless of your filling method. It's always best to run the jets for a few minutes prior to running the heater, to insure all the air from the lines has been bleed. In addition, not all Spa chemistry works well with soft water. Cleanwater Blue is one of the better sanitizing systems to use with any type of water.