Been working on a wall with all the wiring and tubing for my central air unit above my head. Notice a humming seemingly coming right from the tubing and/or wiring. The hum starts followed shortly by the cool air blowing through the house as it should. The unit seems to work just fine, just want to make sure if this is a cause for concern as I am finishing this part of the basement and would rather get it taken care of now rather than after drywall goes up. Thanks.