Ford 2002 F650 Owner's Manual page 112

Driving
Exhaust fumes
Never idle the engine in closed areas. Never sit in a parked or
stopped vehicle for any amount of time with engine running.
If you ever smell exhaust fumes of any kind inside your vehicle,
have your dealer inspect and fix your vehicle immediately. Do
not drive if you smell exhaust fumes. These fumes are harmful and
could kill you.
In order to guard against fumes entering your vehicle, the exhaust
system and body ventilation system should be checked by a qualified
technician:
• Each time the vehicle is raised for service.
• Whenever a change in exhaust system noise is noted.
• Whenever the vehicle has been damaged by impact from another
vehicle, object or road obstruction.
In order to afford proper operation, all air inlet vents should be kept
clear of snow, leaves and other debris.
If you run the engine while stopped (idled) in an unconfined area, open
the windows at least 2.5 cm (one inch) and adjust the heating or air
conditioning to draw outside air into the vehicle as follows:
• If your vehicle has outside air control vents, open them fully.
• Set fan speed on high with function control to any position except
OFF or MAX A/C and the temperature control on any desired position.
• Adjust air control system to force outside air into the vehicle.
Winter fronts
If using an aftermarket winter front (not recommended), it must have a
permanent opening directly in line with the center of the fan drive. The
minimum opening size must be at least 774 square cm (120 square
inches).
The use of an aftermarket winter front or other air flow restriction
device mounted in front of the radiator is not recommended on this
vehicle. Air flow restriction will cause high exhaust temperatures, power
loss, excessive fan usage and a reduction in fuel economy.
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