I have been fixing and replacing parts on my 20 year old system for 13 years. It was trouble free for 7.5 years. The singer system before that went 28 years with zero repairs..28 years.. Anyway, my draft inducer fan on the gas pack is dying and I have one on order that should be here tomorrow or Thursday. But, I'll tell you that air handler is looking rough. Last summer we had nice cold air all summer (after a little R22 was added). But, I think this old dog is on it's last legs. Do I wait for it to completely lay down (like a significant leak or bad compressor, which is only 13 years old and still going strong) or do I start planning to replace?