Arghhh don't ya just hate when this happens.

Was working on an AC unit at a Huddle House.
Checked the unit from head to toe and couldnt' find anything wrong with it.
Pressures, superheat, subcool, amperages, CFM.... everything... right on the money.
But why for it not cool?

The dad blame fresh air for the vent a hood.

It wasn't adding enough fresh air for the hood and made the building go into a vacuum pulling in hot air from every nook and cranny.
Nice breeze coming in the door when ya crack it.