I would advise you to have a Realtor evaluate your home and saleability before spending that much money. That way you'd have more information with which to make a good decision. Of course, a new HVAC unit is a big draw, but the overall condition of your home will have a big effect on how it is priced and how quickly you sell it. In most cases, it sure would be desireable - after all, nothing lasts forever, and it sounds as if you are close the end of its lifetime. If it's not cooling as well as you'd like, it probably is close, and you might want to enjoy the benefits too. We have contractors who give great options to homeowners. After you examine the costs vs benefits, and your personal financial situation, then you might ask a Realtor's opinion. This year, this month, good listings are hard to find in Northern Virginia and buyers are looking hard for a good value. That can change by next year, so the situation might be different. You can reach me at firstname.lastname@example.org if you'd like more info.