It looks like I need to have a wall mounted air handler replaced in a condo and I am wondering if someone knows a good HVAC contractor who does partial replacement and not insists on selling complete systems.

For other small Landlords I think the only way they would sign up with with Credit Agencys to do this is if the agencies actually had a e-payment system service offered to landlords that would handle rent payments and include the info on credit history.

The cold air pumped into every room has to be able to recirculate back to the air handler. 

This is the normal way to handle RE.

You're much better off creating your own mentoring foundation with folks from BP, RE meetups, organizing your strategy which includes your profit centers: CPA, lenders, STR owners in your and other locations who are willing to share their experiences and lists of actions, what to do marketing wise for getting a lot of action, drone handlers to take aerial shots as well as curb appeal etc., meanwhile accepting that price is not alwys the reason people buy or rent.

I have the 17 objection handlers and a contract that you can have however I have no idea how to tell you to contact me without breaking the rules.

In some cases you can do this on your own, in other cases you will need a electrician.Your question about "if this is too big of a project to handle", really depends on your DIY skills and your budget. 

Even their handler indicates they have no rights.

Because of this, the regulations around ESAs become tricky....ESA are required to behave well in public, listen to their handlers, and not cause a disturbance.... 

I was paying $3k for 2.5 ton units (rheem) to replace condensor and air handler, with electric heat.