They have to have a drain to get rid of the condensate.

Since the AC condenser acutally condenses the air pulling the water vapor out of the air and area's like Nick's is said to be dry heat.

Luckily there aren't fines but we are being required to do thousands of dollars of work we planned on doing in a very condensed deadline.

I've read bits and pieces of everything you mentioned in various places, but it's great to have it all condensed into one post to be easily digestible and for reference. 

It could be the condensate drain line from the AC coil.

Installing a condenser (outdoor unit), indoor coil and lineset, as well as the electrical service needed outside, will probably run you 5k. 

depends on size and what parts you need but my last 1200 Sq ft house that needed an A coil, line set, condenser, and a full charge was $1500.

New vinyl windows can pay for themselves in an older home in power bill and keeping condensation damage down around the window.

If condensation on the inside of the windows and/or energy efficiency during the cold months is a big concern, interior or exterior storm windows are options to consider.I'm not a big fan of modern wood windows.

Let's say I upgrade my HVAC to replace old if install new condensation units worth $10000 just for the sake of numbers, how does it impact my depreciationWhat section of tax returns has information about depreciation.Appreciate your inputsThanks.