So, you want to have more cool air being discharged upstairs.To avoid having to rebalance the system every season, most folks just strike a compromise between summer and winter and live with the results.Your HVAC people cannot fight the laws of physics.

But, unless they've been clear they're going to fight it all, I'd focus on the fastest path to getting them gone rather than trying to get all rent due.You've got bigger fish to fry with what sounds like a rehab project starting soon.

You'll have to increase the worth of your "dog in the fight," as it were.

Someone with whom you have "agency" means they are in your corner and fighting for you.

The smallest amount I have gone to court for was about $100 plus my expenses.Other landlords would bribe or pay extortion money to a tenant rather than take up a fight to evict and attempt to collect regardless of the amount. 

I forget what exactly the problem was but people were bringing up issues they've had with roommates fighting and not getting along (which isn't your problem so much.. but still is annoying).But good luck!

I would fight that....

Can I fight the violation?  

They don't have as much money to benefit from some of the loop holes that wealthy individuals take advantage of.The rich fight taxes with money. 

Any thoughts on focusing on areas just outside of GR for rentals instead of fighting with the competition directly in GR?