In my area reputable companies will not switch just the air handler or just the heat pump.

Cash flow is my goal, and I am looking to Memphis because I have a good friend who lives in English Town, I asked his help in identifying the good areas with zip codes. hope to connect and explore this market.

There are lots of good ideas there.2 - Have you explored the local REIAs?

So I'm going to start driving and exploring other ways to find them but would appreciate some advice.How old is too old if a building is well kept up?

The other route that I've explored a bit more is to take on an investor as an equity partner.  

Welcome to the world of Real Estate Investing and the many opportunities available to you.You made the first step in connecting on the largest social network specifically for the Real Estate Investing industry.Take the time to explore all the resources available to you.Networking is how to succeed in this space and as such I wanted to give you an open invitation to feel free to reach out to me at any time.I am located in the Northern Nevada market and doing buy and hold, wholesale and fix and flips… Best of luck with your Real Estate Investing Career.

I would recommend speaking with at least 2 reputable mortgage brokers who have experience with this product. 

Hi Ryland, I'm exploring becoming an agent myself.

You might explore working the owner and asking for the contact info of the people they are working with at the loan servicer.  

Listen to the pod casts and explore the tool bar for areas of interest.