So much so that there are numerous conferences annually for Air BnB investors.

However, he has been complaining of his allergies acting up since moving in and is asking for us to clean the air ducts thinking it is due to dust in the vents.  

I had to hire my inspector to come out and he did two air samples indoor vs. outdoor, and a swab test.

In AIR leases, the most common form leases used nationwide, that provision is at 150% of base rent.If your lease does have a holder over penalty provision you could use that as leverage to enforce prompt payment of the "base" rent.Otherwise I agree with the mention by another that if he's not willing to renew the lease and pay his rent on time then you'll have not choice but to employ the service of a towing service to monitor your parking lot.FYI, most commercial leases, unlike residential leases, have a grace period of ten days.

I've done this in the past when I had some air conditioning units stolen from one of my units.

Just remember, it would have been very easy for them to say, "OK", renew the lease, renew it again when it comes up in the spring/summer, and then just bail on you next October.By trying to work a solution a year in advance, they are, if not doing you a favor exactly, doing better by you than they could have.ME: *WHACK* (Kick you as hard as I can in the nuts)You: *Gasping for air*ME: You should be thanking me, I could have stabbed you.Again on a practical level you are correct that they could have screwed her over even more, but I can't get over how you condone and almost seem to admire these people's behavior.Yes they could be worse but that doesn't mean they aren't jerks that are knowingly trying to screw her over.  

Depending on how they respond you may have to wait until their lease is up for renewal....I had a 4 family with 1 old steam boiler so I was paying the whole house heating bill (what a nightmare)  I ended up seperating adding 2 gas hort water boilers for two first floor units and 2 forced hot air furnaces I dropped into attic for 2nd floor apartments.I planned this major upgrade right when leases were up for renewal and told them there would not be a rental increase for the next 2 years however you would now be responsible for paying your own heat.

You can also add on air conditioner for $6.95 monthly.

Also, the building is very old and the other windows in our apartment would leak air when its windy outside.

Look up Shep Burr...He is local and very active in the Central Florida REIA.Him and his wife both buy/sell/flip/hold properties.