2008 DODGE RAM 3500 CHASSIS CAB air condition

Defrost
Outside air is primarily directed to the windshield
through the defroster outlets located at the base of
the windshield, and the demister outlets located at the
edge of each side of the instrument panel, and the air
conditioning may be on.
Blower Control
The rotary knob on the left of the
control panel is the blower control.
Turn the knob clockwise to one of the
four positions to obtain the blower
speed you desire. To turn the blower
off, turn the knob to the far left posi-
tion.
Temperature Control
The rotary knob at the center of the
control panel controls the temperature
of the interior air. You can choose your
degree of comfort by rotating the
knob. The coldest temperature setting
is to the extreme left (blue region) and
the warmest setting is to the extreme
right (red region) of the rotation.
Circulation
The cab is designed with features to promote outside air
circulation. There are grilles in the cab back panel. These
are air exhausters that provide the means for regular
exchange of cab air.
Side window demisters direct air flow specifically to the
window glass to help prevent interior fogging of the
glass. They are located in the extreme outside upper
UNDERSTANDING YOUR INSTRUMENT PANEL 239
4

edges of the instrument panel. The demisters also pro-
vide extra air ducts for circulation. They are in operation
whenever the Floor, Mix or Defrost modes are in use. To
remove frost from the side windows, it is best to use the
full defrost mode.
NOTE:When you turn off the engine you may hear a
hissing sound from under the hood for a short period of
time. This is a normal condition that occurs if the air
conditioning system has been on. It is not an indication of
a problem with the air conditioning system.Air Conditioning with Dual Zone Temperature
Control Ð If Equipped
With the Dual Zone Temperature Control System, each
front seat occupant can independently control the tem-
perature of air coming from the outlets on their side of
the vehicle.
Dual Zone Control Head
240 UNDERSTANDING YOUR INSTRUMENT PANEL

Air Conditioning and Heating Operation
To turn on the Air Conditioning, set the fan control at any
speed and press the snowflake button located on the
control panel. Conditioned air will be directed through
the outlets selected by the mode control. A light in the
snowflake button shows that the air conditioning is on.
Press the button a second time to turn the air condition-
ing off.
A/C Pushbutton
With the fan control in the ON posi-
tion, pushing the A/C button turns on
the air conditioning compressor. An
indicator light on the button shows
that the Air Conditioning compressor
is on. Conditioned air is now directed
through the mode outlets selected.
Pushing the button a second time turns the compressor
OFF.
Recirculation Pushbutton
Pushing the Recirculation button al-
lows interior air to recirculate continu-
ously in any position except defrost
and defrost/floor mode for rapid cool
down of the interior. See ªFast
Cooldownº later in this section.
Mode Control
The mode control allows you to
choose from several patterns of air
distribution.
NOTE:To improve your selection choices, the system
allows you to operate at intermediate positions between
UNDERSTANDING YOUR INSTRUMENT PANEL 241
4

the major modes. These intermediate positions are iden-
tified by the small dots and give an even blend of both
modes.
Panel
Outside air flows through the outlets located in the
instrument panel. These outlets can be adjusted to
direct the airflow.
Bi-Level
Air flows through the outlets located in the instru-
ment panel and those located on the floor.
NOTE:There is a difference in temperature between the
upper and lower outlets for added comfort. The warmer
air goes to the floor outlets. This feature gives improved
comfort during sunny but cool conditions.
Heat
Outside air flows primarily through the floor out-
lets located under the instrument panel.
Mix
Outside air flows in equal proportions through the
floor and defroster outlets.
Defrost
Outside air is primarily directed to the windshield
through the defroster outlets located at the base of
the windshield and side window demist outlets.
NOTE:The air conditioning compressor operates in
both Mix and Defrost or a blend of these modes, even if
the A/C button has not been pressed. This dehumidifies
the air to help dry the windshield.
Blower Control
The rotary knob on the left of the con-
trol panel is the blower control. Turn the
knob clockwise to one of the four posi-
tions to obtain the blower speed you
desire. To turn the blower off, turn the
knob to the far left position.
242 UNDERSTANDING YOUR INSTRUMENT PANEL

Dual Zone Temperature Control
Use this control to regulate the temperature of the air
inside the passenger compartment. This is accomplished
by having separate temperature control slides for both
the driver and front passenger. The blue area of the scale
indicates cooler temperatures while the red area indicates
warmer temperatures.
Circulation
The cab is designed with features to promote outside air
circulation. There are grilles in the cab back panel. These
are air exhausters that provide the means for regular
exchange of cab air.
Side window demisters direct air flow specifically to the
window glass to help prevent interior fogging of the
glass. They are located in the extreme outside upper
edges of the instrument panel. The demisters also pro-
vide extra air ducts for circulation. They are in operation
whenever the Floor, Mix or Defrost modes are in use.
NOTE:When you turn off the engine you may hear a
hissing sound from under the hood for a short period of
time. This is a normal condition that occurs if the air
conditioning system has been on. It is not an indication of
a problem with the air conditioning system.
Dual Zone Temperature Control
UNDERSTANDING YOUR INSTRUMENT PANEL 243
4

Operating Tips
Fast Cooldown
For a fast cooldown, turn the blower fan rotary knob to
the extreme right position, turn the mode control to the
panel fresh position, press the snowflake button to turn
on the air conditioning, and drive with the windows
open for the first few minutes. Once the hot air has been
expelled, close the windows and press the recirculation
push-button, on dual zone control or switch the mode
from panel/fresh to panel/recirculate on single zone
control. When a comfortable condition has been reached,
choose a mode position and adjust the temperature
control slide and blower speed as necessary to maintain
comfort. For high humidity conditions it may be neces-
sary to remain in the Recirculation mode to maintain
comfort.
Window Fogging
Windows will fog on the inside when the humidity inside
the vehicle is high. This often occurs in mild or cool
temperatures when it's rainy or humid. In most cases
turning on the Air-conditioning (pressing the snowflake
button) will clear the fog. Adjust the temperature control,
air direction and blower speed to maintain comfort.
As the temperature gets colder it may be necessary to
direct air onto the windshield by using MIX Mode
position on the control. Adjust the temperature control
and blower speed to maintain comfort. Higher blower
speeds will reduce fogging. Interior fogging on the
windshield can be quickly removed by selecting the
defrost mode.
Regular cleaning of the inside of the windows with a
non-filming cleaning solution (vinegar and water works
very well) will help prevent contaminates (cigarette
smoke, perfumes, etc.) from sticking to the windows.
Contaminates increase the rate of window fogging.
244 UNDERSTANDING YOUR INSTRUMENT PANEL

Summer Operation
Air conditioned vehicles must be protected with a high
quality antifreeze coolant during summer to provide
proper corrosion protection and to raise the boiling point
of the coolant for protection against overheating. A 50 %
concentration is recommended. Refer to Recommended
Fluids and Genuine Parts for the proper coolant type.
When using the air conditioner in extremely heavy traffic
in hot weather especially when towing a trailer, addi-
tional engine cooling may be required. If this situation is
encountered, operate the transmission in a lower gear to
increase engine RPM, coolant flow and fan speed. When
stopped in heavy traffic, it may be necessary to shift into
NEUTRAL and depress the accelerator slightly for fast
idle operation to increase coolant flow and fan speed.NOTE:On models equipped with Diesel engines, the
idle speed will automatically increase to 1000 rpm at
elevated coolant temperatures to improve engine cooling.
Your air conditioning system is also equipped with an
automatic recirculation system. When the system senses
a heavy load or high heat conditions, it may use partial
Recirculation A/C mode to provide additional comfort.
Winter Operation
When operating the system during the winter months,
make sure the air intake, located directly in front of the
windshield, is free of ice, slush, snow, or other obstruc-
tions.
UNDERSTANDING YOUR INSTRUMENT PANEL 245
4

NOTE:Excessive white smoke and poor engine perfor-
mance will result if manifold heaters are not recycled.
²Heat generated by the manifold heaters dissipates
rapidly in a cold engine. If more than two minutes
pass between the time the WAIT TO START light goes
OFF and the engine is started, recycle the manifold
heaters by turning the ignition OFF for at least 5
seconds and then back ON.
²If the vehicle is driven and vehicle speed exceeds 19
mph (31 km) before the manifold heater post-heat
(after start) cycle is complete, the manifold heaters will
shut off.
²If the engine is started before the WAIT TO START
light turns off, the preheat cycle will turn off.
²If the engine is cranked for more than 10 seconds, the
post-heat cycle will turn off.NOTE:Engine idle speed will automatically increase to
1000 rpm at low coolant temperatures to improve engine
warm-up.
NOTE:When a diesel engine is allowed to run out of
fuel or the fuel gels at low temperatures, air is pulled into
the fuel system.
You may try priming as described below.
1. Add a substantial quantity of fuel to the tank (5 to 10
gallons) or eliminate the gelled fuel condition.
2. Crank the engine for 1 to 2 seconds. If the engine does
not start, then release the key or starter button back to the
RUN position (do not turn the key back to the OFF
position). The electric fuel transfer pump will continue to
run and purge air from the system for about 20 seconds.
After 20 seconds, attempt to start the engine again.
3. Start the engine using the Normal Starting Procedure.
260 STARTING AND OPERATING