49 CFR § 374.313
Equipment
November 18, 2020
(a) Temperature control. A carrier shall maintain a reasonable temperature on each bus (except in commuter service).
(b) Restrooms. Each bus (except in commuter service) seating more than 14 passengers (not including the driver) shall have a clean, regularly maintained restroom, free of offensive odor. A bus may be operated without a restroom if it makes reasonable rest stops.
(c) Bus servicing. Each bus shall be kept clean, with all required items in good working order.