Check your ducting it needs to be maintained

www.supercell.co.nz has a full range of flexi ducting for all Air conditioning & ventilation & extraction from $36 a length..

Nude, insulated, clip lock, all sizes all lengths for all jobs.

Check your ducting,, if its going gray, transparent, or ripped even attacked by rats you need to replace it or you're losing any benefit from the AC or dry ventilation air. 

Its super easy to DIY...

www.supercell.co.nz