I had a daiken inverter ducted installed a couple of weeks ago & when the unit is one I hear this ticking noise from the vents. It's like a noise you would hear when metal is cooling down. For example when you have been cooking & you turn the griller off & you hear the metal sound going from one temperature to another.
I have a steel framed house & yes at times I hear a metal sound on a hot night with the change of temperature, but I don't think it's my steel frame.
The ducting had a cotton insulation inside the vents & I am wondering if it's not well covered or something.
Could there be something wrong.