Arrived to remedy an inoperable system. Upon inspection of the system found it displaying a fault code relating to the furnace overheating. Tested systems gas pressure and determined it is burning gas properly. Tested systems airflow and found that the furnace is choked up on the supply side. Inspected the inside of the furnace and found that the evaporator coil is heavily impacted in debris and is not allowing air to flow through it. Found that the furnace fan is coated in dust debris. The furnace can’t move the proper amount of air when it is so coated in debris. Either of these issues alone would be enough to cause the system to overheat. Called land lord to review repair solutions. Was unable to get in touch but left voice mail.