I have a comfortmaker RPJ2 furnace from 1991 and an AC condensing unit from 1991 as well. Last year the blower on worked intermittently with AC. I had to go spin the blower manually to give it some help starting. I replaced the starter capacitor and it worked fine the rest of the Summer. This year it is dead. It is not even trying to start with AC or the manual fan switch on. It works fine with the furnace though which seems a little odd... Someone came out a looked at it and said the control board was bad. I found one for about $125 online. I am sure I could probably replace it myself but I am wondering if I am just going to start running into other problems with a system this old. The AC unit needed to be recharged last year (3 pounds) so there is most likely a leak in the line somewhere too. Would my best bet be to fix the control board and just replace the AC or should I just replace everything at once? The person I had come out quoted me $3100 installed for a 2.5 ton 13 seer comfortmaker and 80,000 BTU 95% efficient furnace. Seemed like a decent enough price to me.

Might be too open-ended, but I'm curious what goes into a typical 'service' of a central a/c system, whether it's the air handler or the compressor unit outside. How often should there be a service or preventative maintenance? Is it something a mechanically inclined person can do? Thanks.