I have two rentals. PM said the AC looked old and ask me to buy

I have two rentals. PM said the AC looked old and ask me to buy Fidelity warrenty.  Should I buy it?  He said each AC change will cost at least $6000,  home warranty only cost $6-700 a year, and my rental AC needs to change in 1-2 years.  That will save me a lot of money.  But I remember everyone said don't by home warrenty.  So I am not sure what to do....