Replace Old Furnace and window AC with new HVAC???

[Kraig Krueger]

I am purchasing a 1970's SFH locally in Minnesota as a long term rental that has new siding, windows, roof, and a new kitchen, but has a Lennox furnace from 1999, and a window AC unit on the main level. Both are still in working condition. The main level is about 1100 square feet, and it has a 1,000 square foot un-finished basement.

I'm trying to decide if I should replace the furnace right away and add central air, or if I should just get a tenant in and replace it once there is a problem?  Most of the other "big ticket" items are new in the house. This will be our third single family rental.  I appreciate your thoughts!

Kraig