A lot of cars back in the 80s (Hondas, Nissans, et al) had many of their A/C units installed at the dealer.
Even back in the late 80s many Mazdas got dealer installed A/C units.
The Asian cars were pretty easy to do this on The bulk of the wiring was in place and the A/C kits were pretty much plug and play. Nissan trucks paid something like 6 or 7 hours for the install and after a few to get acclimated with they could be done in 3 or 4 hours.
I remember back in the late 80s a real oddball Subaru came in with an A/C that would not cool. Pressures were fine and the unit had just been installed by a Subaru dealer in eastern OK. I evacuated the system and during charging found it would only take 2/3 of a small can. WTH? Re-evacuated it and tried again. Same thing; 2/3 of a 12 ounce can was it.
At that point i took a flashlight and went hunting. Come to find out the condenser was 10" X 10" and the evaporator was the size of one of those small Hormel Black Label hams. I have no idea where those clowns at the dealer got that A/C kit but it was a total joke.
I wrote it all up and suggested the car owner pay a visit back to that dealer for a real A/C kit because that one was never going to work on an 80 degree day; much less a normal 100 degrees+ day.