I wouldnt put $1600 into a 10 yr old unit today. Once stuff starts to go, and you start having to replace major components (reversing valve, expansion valve, TXV valve, coils, condenser, compressor, etc) it's generally better to just bite the bulllet and get a new unit. Not to mention the fact that due to all the refrigerant changes over the past 15 yrs, you might not even be able to get the parts for your older unit, that you need to keep it running a year now, when something else goes bad. You're lucky to get 12 yrs out of most units now days, even if it is properly maintained. They just dont make things like they used to, and that's a fact.