Jim, 26 years out of an AC system is honestly pretty impressive! I’m a bit of a DIY girl myself, so I completely understand why an $18,000 quote immediately makes you think, “I could probably do some of this myself.” 😂 I’d definitely get a couple more quotes before making that decision though. From what I understand, replacing an older system isn’t always as simple as swapping the outside unit. The new condenser has to work properly with the indoor coil and furnace/blower, and with a system this old there may also be differences in refrigerant, electrical requirements and the existing lines. If it were my house, I’d ask them to break that $18K quote down line by line so I could see exactly what I’m paying for. I’d probably be perfectly happy doing some of the removal, mounting or other mechanical work myself, but I’d leave the refrigerant charging and final commissioning to an HVAC tech. And before replacing the furnace automatically, I’d want someone to explain exactly why it needs replacing. I’m all for DIY, but I’m even more in favor of not replacing something that still has useful life left in it