Since we have deals in multiple states (CO, IL, TX, OH, GA, and PR) I prefer working with one national company who can handle everything.  

I realize it may need piping, coils replaced as well. 

Folks,It is possible to build a Passivhaus compliant home (energy consumption <=15kWh/m^2 per annum) using off the shelf materials with a marginal increase in construction costs (~10-15% ... less as the workforce becomes more skilled).Primary heating and cooling of such a home can be accomplished via the ERV/HRV system with a small auxiliary heating source (there's a house here that has a 1500w auxiliary coil to provide additional heat to the fresh air supply during the coldest part of winter ... that's essentially replacing your furnace with a hair dryer).Even a near-Passivhaus construction (or retrofit) can lower energy costs 70% or more in comparison to the conventional (or even R2000) house being built in Canada these days.  

In talking with our real estate agent it was suggested that we coils raise rates after the existing tenants move out and I think it's definitely viable.

Payne is not the best system try brant should be same ball park.Also after you pay the 475 for the repairs you can open a cash account at a supply place and order the units and the coil line and just get it installed and will save you some money alot of the mark up is on the equipment.IF you go to a 2rd party vendor they will do it 1st party most of the time will tell you no they want you to have a HVAClic  you will  save about 20% of the cost .

Even the great tenants who are always on time don't change them or if they did it's when you remind them the third time after 3 months...I would give them 12 filters and at the end of the lease there are still 11 new filters and the original one completely disintegrated and become "mush" on the coil above it.So now I always change it every 30-45 days myself, and use it as a way to do a quick inspection of the property.But too many odd size filters for each property or each individual unit is a real pain.

The coils and fans become very moldy and nasty.

He said he couldn't go any higher, as the coil was limiting him.Well, previous to installing the AC unit  the temperature in the home was 78 degrees when it was 95 degrees outside.

If central a/c I check the HVAC evaporation coils.

Not to say I wouldn't considering representing, but I don't think theres a large enough clientele out there that values a socially awkward realtor showing up in a multicolored Accord, ripping cabinets down and chasing roaches around with an air nailer.