If it's starting slowly It would be my guess that it might be dirty or need lubrication. Can you remove the whole blower assembly and clean it out real good and lube the motor (if you can).
The blower motor on one of my split system blowers is now
about 20 years old. Had the tech check it last season since I thought it started up a bit slowly, but he said it was ok; I am wondering if I should have it replaced before the next heating season since it is located in a very tight attic space with difficult access. Is 20 years time for a replacement even though it seems to be working fine?
If it's starting slowly It would be my guess that it might be dirty or need lubrication. Can you remove the whole blower assembly and clean it out real good and lube the motor (if you can).
if it's a real difficult job to remove,and you plan on trying to keep your 20 yr old system running(which is probably at the end of it's lifespan),you might as well replace the motor when you clean the blower assembly.Not worth your time to go back in there........JMO
If everything was always done "by the book"....the book would never change.
15-18 years at best.
Now I have seen a few over 24 years old but not often I see motors with that much age still running.
If it's still doing the job for you leave well enough alone, "don't fix what's not broken"
i personally wouldn't put a dime into a 20 year old system.
it's time to start the research on a new higher efficiency system, while you have the time on your side.
by the way, effective jan. 2006, manufacturers can no longer produce equipment under a 13 seer efficiency. depending on where you live, the extra cost for a 13 may never be paid back over the life of the system.
start shopping.