Would you buy a duplex with no central air system?

[Sean Murphy]

I'm interested in a duplex in my area, but there is no central air system installed in the home, and the heat is baseboard electric. My initial reaction is to be concerned that window A/C units may not be satisfactory for the long term holding of this property, but I have no idea how much money it would cost to install a new system down the road. Right now the tenants in the home pay their own electric, which covers the costs of running the window units. The numbers work well for this property, but I'm wondering if anyone has any experience with properties that have similar air conditioning and heating systems, and if any issues have come out of it. 

I appreciate everyone's help!