He is correct. The shorter lifespan is because of the widespread use of aluminum coils now instead of the old copper ones. The braised aluminum joints aren't as strong as copper and they tend to blow up with the higher pressure of the new R410A units VS the old R22 units.

That's not to say every aluminum A-coil is going to get a blow out, but a lot more of them do then the older copper coils.

He stated that ACs will only "last a couple of years at best". Please provide data to support this opinion. Oh, and by the way, R410 units have been available for at least 17 years so they are hardly "new".

Why not get home warranty. They will replace ac and roof of it can not be fixed. My ac was 20 years old and they still fix unit with new compressor. Heat same age and they replaced circuit board and two new fans. When my home here reaches ten yrs will buy new warranty.

What companies insure roofs over 15 years?

have you had yearly maintenance done consistently on the AC? if so, what does the AC tech say (granted they always want to see you a new one) who knows how long it will last but I will tell you from living in Florida for over 40 years and speaking from past experience, it will go on a Friday just after business hours of a long weekend on the hottest day of the year.

Regardless of what maintenance has been done, an HVAC technician cannot tell you how long your system will last. But, at 20 years, it is a good time to buy a new system, whether it is working or not.

You've been provided with enough information to do your own research. The widespread use of aluminum coils certainly is new, although as self proclaimed gatekeeper of everyone else's comments I'm sure you're well aware even if it doesn't appear so to the casual observer.

Spare me the snarky comment. The statement that an AC will "last a couple of years at best" is absurd. If you believe it then provide data to support it. Otherwise, your opinion is worthless.