2003 CHEVROLET C/K ad blue

2-67
The eight-wire harness contains the following
trailer circuits:

Yellow: Left Stop/Turn Signal

Dark Green: Right Stop/Turn Signal

Brown: Taillamps

White: Ground

Light Green: Back
-up Lamps

Light Blue: CHMSL

Red: Battery Feed

Dark Blue: Trailer Brake
Trailer Connections (C6/C7/C8
Models Only) (If Equipped)
If your vehicle has these trailer connections, they are
located at the rear of the cab for a tractor and at the rear
of the chassis when towing a trailer. There will be an air
connection and an electrical connection.
Be sure that the couplings to the trailer are
made correctly.
Air Connections
If you are not connecting the trailer air line connections
to another piece of equipment, be sure to replace their
protective caps.
Electrical Connections
This system is a seven-wire cable that will connect to
the trailer, supplying power to the trailer's lighting
system. When not in use, it is stored in the trailer
air
-hose storage bracket.
NOTICE:
Starting in 1998, the center pin (also known as
the auxiliary circuit) of the seven
-pin trailer
electrical connector will be wired to provide
continuous power for the trailer anti
-lock brake
systems when the ignition key is in the on
position. Care should be taken to insure that
continuous power on this circuit will not cause
damage to the trailer electrical system.
Consult with the trailer manufacturer for the
proper operation and checking procedures for
the trailer anti
-lock brake systems.

3-2
Comfort Controls
This section tells you how to make your air system work
for you.
With these systems, you can control the heating, cooling
and ventilation in your vehicle.
Heater Controls
If your vehicle does not have air conditioning, the
control panel will look like this.
Fan Knob
The knob on the left side of the control panel regulates
the fan speed. The knob has four speeds. To increase
airflow, turn the knob clockwise. To decrease airflow,
turn it counterclockwise. To turn the fan off, turn the
mode knob on the far right all the way
counterclockwise.Temperature Knob
The middle knob on the control panel is used to adjust
the temperature of the air flowing into the passenger
area of your vehicle.
Turn the knob toward the red area for warmer air. Turn
the knob toward the blue area for cooler air.
Mode Knob
The knob on the right side of the control panel is used to
select the direction of the air flowing into the vehicle.
(Vent): This setting directs air through the
instrument panel vents.
(Bi-Level): This setting divides airflow between
the floor vents and instrument panel vents.
(Floor): This setting directs air through the
floor vents.
(Defog): This setting divides airflow between the
floor vents and windshield.
(Defrost): This setting directs air through the
windshield vents. This setting is used to remove fog or
ice from the windshield.

3-3 Heater/Air Conditioning Controls
(If Equipped)
If your vehicle has air conditioning, the heater/air
conditioning control panel will look like this.
Fan Knob
The knob on the left side of the control panel regulates
the fan speed. It has four speeds.
To increase airflow, turn the knob clockwise. To
decrease airflow, turn it counterclockwise. To turn the
fan off, turn the mode knob on the far right all the way
counterclockwise.Temperature Knob
The middle knob on the control panel is used to adjust
the temperature of the air flowing into the passenger
compartment of your vehicle.
Turn the knob toward the red area for warmer air.
Turn the knob toward the blue area for cooler air.
Mode Knob
The knob on the right side of the control panel is used to
select the direction of the air flowing into the vehicle.
(Maximum Air Conditioning): Turn the right
knob to maximum air conditioning for maximum
cooling. This setting puts the system in the recirculation
mode and helps to maximize your air conditioner's
performance and your vehicle's fuel economy. This
setting also cools the air the fastest. After the vehicle's
interior reaches a comfortable temperature, turn the
knob clockwise to place the air conditioning system in
the regular air conditioning mode.
(Air Conditioning): This setting is used for
normal cooling on hot days. It cools outside air and
directs it through the instrument panel vents.

3-4
(Bi-Level Air Conditioning): This setting divides
airflow between the floor vents and instrument panel
vents. The air conditioning compressor will cycle
continuously in this setting as long as the outside air
temperature is warm enough to activate the compressor.
(Vent): This setting directs air through the
instrument panel vents.
(Floor): This setting directs air through the
floor vents.
(Defog): This setting divides airflow between the
floor vents and windshield vents.
(Defrost): This setting directs air through the
windshield vents. This setting is used to remove fog or
ice from the windshield.
Air Conditioning (If Equipped)
Before using the air conditioning, open the windows to
clear the vehicle of hot air. This reduces the time it takes
for your vehicle to cool down. Then keep your windows
closed for the air conditioner to work at its best.You can use maximum air conditioning with the
temperature knob in the blue area when it's really hot
outside and you need to cool the inside air quickly.
Maximum air conditioning lets in only a little air from
the outside.
If you first use maximum air conditioning, you can then
use regular air conditioning with the temperature knob
in the blue area, as soon as the vehicle has cooled down,
so outside air will be going through your vehicle.
While in maximum air conditioning, regular air
conditioning, bi
-level air conditioning, defog or defrost
mode, you may notice a slight increase or decrease in
engine speed, due to compressor operation. This is
normal because the system is designed to cycle the
compressor on and off to maintain the desired
temperature.
Heating
On cold days, use floor with the temperature knob in the
red area. Outside air will be brought in, heated and
distributed through the floor vents. The heater works
best if you keep your windows closed while using it.
If you use the optional engine coolant heater before
starting your engine, your heating system will produce
warmer air faster to heat the passenger compartment in
cold weather. See ªEngine Coolant Heaterº in the Index.