As the buyer I would expect you to offer cash for up to half the value of a replacement A/C unit that is of generic quality. So figure about $3k+. As the seller I would try and hold out and offer nothing. But come on it is a 17 year old unit. It is going to fail. And if it needs Freon, that unit is going to just be replaced. No buyer wants to worry about replacing the HVAC right after they buy the house even if you do have the warranty. Replacing the unit is a hassle. If you did a major remodel, that would seem to apply you are selling to the turn key crowd, not the fixer upper crowd. As a buyer I hate the AHS warranties. I find zero value in them. I want to be able to pick my own service company. Not use the cheapest POS company that the insurance company uses. I also want to pick the piece of replacement equipment, not have the insurance company put the cheapest POS equipment on my property. You can try to assign value to that home warranty during negotiations. It’s a crapshoot. Maybe the buyer will take your offer at face value. You get lucky. Maybe you get a buyer like me that if they felt they had leverage in a buyers market would turn the screws and be willing to walk away over something like this. You can always ask the realtors to pitch in some cash to close the gap if negotiations breakdown but the deal is close.