Judge it by the difference, not by how cold it feels
Everybody assesses air conditioning the same way: they put a hand in front of a vent and decide whether it feels cold. That is a poor test and it is particularly poor in a hot climate.
What a system actually does is remove a certain number of degrees from the air passing through it. That capability is roughly constant. What changes is where it starts.
On a 75 degree day, a healthy system produces air that feels properly cold, because it is starting from a comfortable temperature and taking it well down. On a 105 degree day, the same system, working exactly as well, produces air that feels merely cool, because it is taking the same number of degrees off a much higher starting point.
Which means a driver's impression of the air conditioning in July tells you very little. A system can feel disappointing and be performing to specification, and another can feel acceptable in spring while being substantially down.
The way to know is to compare the vent temperature against the outside air temperature rather than against expectation. That is a measurement rather than a judgment, and it is what a proper assessment involves.
What that means for when you book
Having it checked on a mild day gives a cleaner result than having it checked on the hottest day of the year, when every system in the state is struggling with the conditions rather than with a fault.
It is also the point: a system assessed in spring can be repaired before the weather makes it urgent. See scheduled maintenance.
What usually goes wrong
The national A/C service page covers the common faults and why a recharge without finding the leak is temporary.
About this store
The Fernley store runs sixteen services and is managed by John Jangula.
See the national A/C service page for all 33 locations.