Improving Value on a Rental

[Billy Daniel]

I've bought into the idea that I should try to increase the value of a rental property by 10% in the first year of ownership.  I've also noticed that there are numerous houses in my area (Arkansas) that do not have central heat/air.  My question is: Would installing a central heating and air conditioning unit meet my 10% improvement rule?  We break 100F during the summertime, so I feel like it would, but want to hear advice from the pros!

Also, if the A/C won't do it, whats the best "bang for my buck" to reach my 10%?