fresh air rapidly displaces stale air as the cab pres-
surizes.
IMPORTANT: To prevent the buildup of fumes or
odors inside the cab (for example, from smok-
ing),
do not operate the heater and air condi-
tioning system in a recirculation mode for more
than 20 minutes.
Defogging and Defrosting Using
Fresh Air
1.
Turn the temperature control switch all the way
clockwise for warm air, the fan switch to off and,
if equipped, the bunk fan switch to off before
starting the engine.
2.
Remove any ice or snow from the outside of the
windshield, door windows, and fresh air inlet
grille.
3.
With the engine at operating temperature, turn
the fan switch to 4, the highest speed. See
Fig. 4.9
. Leave it in this position for 30 seconds.
This will clear the system of moist air.
4.
Move the air selection switch to the defrost
(windshield) position. In this position warm, dry
air is directed to the windshield.
NOTE: The air conditioner, if equipped, is auto-
matically engaged in the defrost mode. This
dries the air.
Heating
1.
With the engine at operating temperature, move
the temperature control switch all the way clock-
wise for heat. See
Fig. 4.10
.
2.
Turn on the fan switch to the desired speed.
3.
Move the air selection switch to the desired set-
ting.
IMPORTANT: If the windows start to fog, move
the air selection switch to defrost (windshield)
and make sure the fan is on. To defog the driv-
er’s door window, turn the extreme left dash-
face outlet to direct airflow to the upper left.
NOTE: In mild weather the fan switch can be
kept off since forward motion of the vehicle will
provide airflow through the heater.
4.
If the vehicle has a sleeper climate control panel,
set the controls as desired. Refer to "Heating,
Auxiliary Heater and Air Conditioner."
5.
When a comfortable temperature has been
reached, adjust the fan switch setting and tem-
perature control as needed to maintain the tem-
perature.
IMPORTANT: To prevent the buildup of fumes or
odors inside the cab (for example, from smok-
ing),
do not operate the heater and air condi-
tioning system in a recirculation mode for more
than 20 minutes.
Air Conditioning
IMPORTANT: Operate the air conditioner at
least five minutes each month, even during cool
weather. This helps prevent drying and cracking
of tubing seals, reducing refrigerant leaks in the
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1
2
3
1.
Fan Switch at Highest Speed
2.
Air Selection Switch at Defrost
3.
Temperature Control Switch at Warm
Fig. 4.9, Defogging and Defrosting Settings
9/07/95
f830719
1
2
3
4
1.
Fan Switch
2.
Air Selection Switch
3.
Temperature Control Switch at Warm
4.
Fresh Air/Recirculation Switch
Fig. 4.10, Heating Settings
Heater and Air Conditioner
4.6