Should I replace the Ac?

[Allen Lopez]

So I have a SFH that I am renting. The property is in great shape. The Ac is a bit older, and the inside has rusted to the point that I have had to call the Ac Mecahnic to con and give it a good cleaning. He stated that it will happened again, but the Ac is working fine after. Should I just go ahead and replace it or should I jut run it until it dies. If I run it until it dies, I might be able to get 2 more years out of it, but the tenants might be without Ac for a week. This would be an inconvenience. Additionally, if I plan it it it gives me a chance t o shop around instead of just getting something after it happens and end up over paying.thoughts? Thank you