Do I let my tenant fix an AC unit?

[Rich Rodman]

It's summer in Cleveland which means it's nice and hot outside. One of my units doesn't have central air but rather has a few AC units. My tenant found one of my old AC units in the garage (I have it in case I need parts) and has offered to get it fixed. She said that if she pays to get it fixed, she expects to keep it. 

I have no need for this AC unit, but my question lies in "training" my tenants. If I allow her to fix this one and keep it, am I setting a standard for other tenants? Should I tell her to buy a new AC if that's something she feels she needs?