Arrived today for poor cooling in back of building. Checked system everything is working properly at this time. Explained to customer they need to keep doors closed in mechanical room and water heater room to keep from pulling heat air back into the area. This is making the air conditioner work extremely hard. Also customer stated the thermostat is stuck so you cannot change settings on the thermostat. It looks like the building used to have 7 systems on it. But there’s only 3 this could also be a problem.