D.C. Mun. Regs. tit. 14, r. 14-510
The owner of a rental habitation, who provides air conditioning as a service either through individual air conditioning units or a central air conditioning system, shall maintain such unit or system in safe and good working condition so that it provides an inside temperature at least fifteen degrees Fahrenheit (15° F.) less than the outside temperature.
The owner shall also have the individual units or central system inspected each year, between September 1st and May 1st, by a master refrigeration and air conditioning mechanic or master refrigeration and air conditioning mechanic limited, licensed by the District of Columbia to ensure compliance with this section and with the Fire Prevention Code (12D DCMR F101.6(5)).
The findings on inspection shall be recorded on forms approved by the Department of Consumer and Regulatory Affairs ("Department") within fifteen (15) days following inspection and shall be delivered to the owner, who shall file a copy with the Department within seven (7) days of receipt of the findings.
The owner shall correct all defects as found upon the inspection by June 1st of each year, and shall submit written certification to the Department that the corrections have been made.
The written certification shall be signed by the owner and by a master refrigeration and air conditioning mechanic, or master refrigeration and air conditioning mechanic limited, licensed by the District of Columbia.
D.C. Mun. Regs. tit. 14, r. 14-510