> That is to say, as soon as something goes wrong with them, they are garbage.
Can you unpack what you mean by this? Standard A/C's can be repaired - fans can be replaced, as can compressor motors. Also, better and more efficient heat pumps can be more sensitive to maintenance (or lack thereof), because they often achieve that efficiency through finer control of mechanical components or lower resistance components.
IMO, a bigger factor in the longevity of traditional A/Cs is that they tend to have single-stage compressors that are over-sized for their loads most of the year, resulting in short-cycling and therefore shorter equipment life.
Just because something "can" be repaired doesn't mean it makes sense to. With most appliances if you are going to hire something to fix it outside of warranty it will cost hundreds of dollars at a minimum and you are often not guaranteed a repair will work. Even if it is in warranty, often a replacement part will be needed that is not available or is not economical to have a person install versus replacing the whole unit and the company will just scrap the whole thing and give you a replacement (after you've spent hours on phone calls, emails and talking to technicians).
The most egregious example of this I will highlight is electronics. Ask any manufacturer to provide a replacement board for an otherwise functional heat pump, air conditioner, etc. They likely won't have one. And even if they do, are you now going to hire someone to replace it? Do it yourself? If you aren't mechanically inclined its option one which can be hundreds of dollars and if its option two you will now be doing it likely with no or poor documentation spending how much of your time?
Heat pumps are no more sensitive to maintenance than air conditioners (besides the use of longer hoses for the refrigerant movement giving more opportunities to generate leaks). Or atleast their nature doesn't mean they inherently need to be (maybe that's the better way to put it). Compressors, fans, radiators, inverters, these are things that have been made for decades and if you walk into any commercial manufacturing space you'll find examples last for decades. That level of quality just isn't offered for homes.
You are absolutely correct that over-specifying heat pumps is also a big issue. That's kinda've a whole nother topic though that we could get into along with energy modeling, regualtions/practices, etc.
We have a decent-quality Mitsubishi unit that's 7 years now. Last year, one of the main boards died. Living in a country with strong consumer protection, I was able to argue my way into having Mitsubishi cover the cost of a new board, I just had to cover labour.
If I'd had to cover all the cost, it would have been more than 40% of the cost of a new unit, and then you start asking yourself if it's worth it.
Even though the marginal cost of the main board is likely below $50, the replacement ones sell for close to $500.
Can you unpack what you mean by this? Standard A/C's can be repaired - fans can be replaced, as can compressor motors. Also, better and more efficient heat pumps can be more sensitive to maintenance (or lack thereof), because they often achieve that efficiency through finer control of mechanical components or lower resistance components.
IMO, a bigger factor in the longevity of traditional A/Cs is that they tend to have single-stage compressors that are over-sized for their loads most of the year, resulting in short-cycling and therefore shorter equipment life.