Spa Jets

First with spa jets, you are supposed have air in the lines as that is what cause the bubbles to occur. The vent with the holes is filled with water when the pump is off but when it is turned on, the venturis in the jets suck the water out so air can travel to the jets and get mixed with the water. This can cause a gurgling sound out of that pipe because not all the water is removed so that is not unusual.

Second, if you have only a couple jets that are not working, it is most likely due to an obstruction in the water lines. This is not uncommon in new builds and can usually be cleared buy removing the outer jet fittings and inner nozzle (with a long socket wrench depending on the type of jet) and then flushing out the lines.

You sure the air is being sucked in from your blower line? Pull the blower off the pipe and tape or plug it closed and confirm that line is causing your problem.

That air valve by the spa could not be working properly.

The check valve has a spring and the blower would be strong enough to override the spring whereas the spring should keep the pipe closed without the blower running.