It has nothing to do with sucking hot air in. Nor does it have anything to do with sucking hot air out. A/C systems don't suck air between the house and the outside at all.hennyj15 said:
Not trying to call you out in particular but it's a common misconception.
AC systems suck hot air out from inside your house. They don't take hot air from outside and make it cold to put in your house.
Always makes me giggle when I drive though poor neighbhoods and they have lean-tos built over their outdoor units.
OP is right that a cooler temperature of the air around the outside AC unit allows it to exchange heat better with less load on the compressor. This is a simplified read about it:
https://sciencing.com/can-outside-temperature-affect-central-ac-23326.html
For reinforcement, search this page for "don't forget about your air conditioner unit" and read what it says:
https://energy.gov/energysaver/articles/little-shade-can-go-long-way
It is actually recommended to install exterior a/c units on the north side of a house, if possible, and failing that, to install them in an area with plenty of shade.