Peterbilt Model 320 Operator's Manual after 8-07 - Peterbilt Motors ...

Heating And Air Conditioning Controls
PART 4: CONTROLS AND DISPLAYS
If your vehicle is a tractor, a red, octagonal-shaped knob
will be next to the parking brake valve on the right-hand
control panel. This is the trailer air supply valve for selecting
operation with or without a trailer
WARNING! Stopping with the parking brake
controls can cause a sudden wheel lock-up,
loss of control, or can cause you to be overtaken
by following vehicles. You could be
severely injured. Never pull out the parking
brake valve while the vehicle is moving.
Heating And Air Conditioning Controls
02909
Two-Valve System
• To apply all parking brakes, pull the yellow, or parking
brake, knob out. The truck or tractor parking brakes
will set. If equipped, the Trailer Air Supply Valve (red
octagonal knob) will automatically trip (“pop out”) and
set the trailer parking brakes.
• To release truck parking brakes, push in the yellow
knob. If a tractor with trailer, push in both the yellow
and the red knobs.
For full information on parking brakes, see the Index, under
Brake.
WARNING! Exhaust fumes from the engine contain
carbon monoxide, a colorless and odorless
gas. Do not breathe the engine exhaust gas.
A poorly maintained, damaged or corroded exhaust
system can allow carbon monoxide to enter
the cab. Entry of carbon monoxide into the
cab is also possible from other vehicles nearby.
Failure to properly maintain your vehicle could
cause carbon monoxide to enter the cab and
cause serious illness.
– 36 – Y53-6015 R(08/07)