Page 115 of 272

UNDERSTANDING YOUR INSTRUMENT PANEL 115
4
Residual Engine Heat Utilization (REST)
The REST switch (1) is located on the
center section of the dashboard.
The residual engine heat utilization
system can be used to keep the
vehicle interior warm for some time
after the engine is switched off.
Turn the key to position 0 in the ignition lock or
remove it altogether.
To switch on:
1. Press the residual engine heat utilization switch (1),
the indicator lamp (2) lights up.
The blower will run at speed 1 regardless of the
setting of the airflow control.
2. Set the temperature control as required, refer to
"Heating, Ventilation".
To switch off:
Press the residual engine heat utilization switch (1)
again, the indicator lamp (2) goes out.The residual engine heat utilization is automatically
switched off if:
1. If the key is turned to position 2 in the ignition lock,
2. after about 30 minutes,
3. if the battery voltage is too low.
A IR CONDITIONING, REGULA TED (OPTIONA L)
The air conditioning switch (1) is
located on the center section of the
dashboard.
The air conditioning can be used to
cool or dehumidify the air in the
vehicle. The selected temperature is
reached as quickly as possible and
then held constant.
The air conditioning is only operational when the
engine is running.
Freightliner-all.book Pag e 115 Monday, December 1, 2003 2:54 PM
Page 120 of 272
120 UNDERSTANDING YOUR INSTRUMENT PANELAir StrainerTo lock fasteners (1)
To unlock fasteners (2)
The air strainer is located at the rear of the air
conditioner for rear passenger compartment.
Increased quantities of sand or dust may settle on the
air conditioner for rear passenger compartment air
strainer when driving on dusty or sandy streets. The
air strainer must be either cleaned or replaced in the
event of visible contamination.Removing and Cleaning the Air strainer
1. Unlock all quick-acting fasteners (2).
2. Remove the cover and air strainer (3).
3. Remove the Velcro closure (4) from the cover (6)
and the grating (5).
4. Remove the air strainer (3) from the grating.
5. Wash out the air strainer (3) with clean water.
6. Let the air strainer (3) dry.
NOTE: The air strainer (3) must not be cleaned or dried
by machine.Freightliner-all.book Pag e 120 Monday, December 1, 2003 2:54 PM
Page 121 of 272

UNDERSTANDING YOUR INSTRUMENT PANEL 121
4
Installing the Air Strainer
1. Affix the air strainer (3) to the grating (5) (make
certain that the ends project evenly).
2. Replace the air strainer (3) and grating (5) on the
cover and press the Velcro closure (4) on the
cover (6).
3. Insert the air strainer (3) with the cover and
grating (5).
4. Lock (1) all quick-acting fasteners.
ELECTRIC BLOWER (OPTIONAL)See Section 4, Understanding Your Instrument Panel,
for switch locations.
The electric blower can be used to
aerate or deaerate the cargo area.
This feeds fresh air into the cargo
area or extracts warm air.
Deaeration:
Press switch upward.
Aeration:
Press switch downward.
To switch off:
Switch the airflow switch to the center position.
CAUTION!
Never operate the air conditioner for rear
passenger compartment without an air strainer.
Never install a damaged air strainer.
If the air strainer with visible contamination is
neither cleaned nor replaced, damage to the air
conditioner for rear passenger compartment may
result; such damage is not covered by the
Warranty.
Freightliner-all.book Pag e 121 Monday, December 1, 2003 2:54 PM
Page 122 of 272

122 UNDERSTANDING YOUR INSTRUMENT PANELHEA TER BOOSTER
The switch (1) for activating the
heater booster system is located in
the center section of the dashboard.
The heater booster system can be
switched on while the vehicle is
being driven to help the engine to
reach its normal operating
temperature more quickly, which
will help to heat up the passenger compartment as
quickly as possible when the heating is switched on.To switch on with the engine running:
Press switch (1), the indicator lamp (2) lights up.
To switch off:
Press switch (1) again or switch the engine off. The
heater booster will then switch to run-on mode (about
2minutes).
NOTE: When the vehicle is being driven and a coolant
temperature of over 185 °F (+80 °C) is reached, the
heater booster system will switch to regulation mode.
If the coolant temperature drops to below 167 °F
(+75 °C) with the heater booster system switched on,
heat output is increased again.
If the key is turned to position 0 in the ignition lock
(run-on for about 2 minutes), the last setting selected at
switch (1) is retained when the engine is restarted
(memory function).
The operation of the heater booster system is usually
not required at outside temperatures above 41 °F
(+5 °C).
Freightliner-all.book Pag e 122 Monday, December 1, 2003 2:54 PM
Page 130 of 272

130 UNDERSTANDING YOUR INSTRUMENT PANELTo switch on at blower speed 1:
Press the upper section, the left-hand indicator lamp in
the switch lights up.
To switch on at blower speed 2:
Press the lower section, the right-hand indicator lamp
in the switch lights up.
To switch off :
Press the switch to the middle position.
Operation is only possible when the key is turned to
position 2 in the ignition lock.
NOTE: The auxiliary heat exchanger in the load
compartment should be switched off at coolant
temperatures below 176 °F (+80 °C) to quickly de-fog
and de-ice the windshield and front side windows.
A UXILIA RY HEA TER – TIPS FOR COPING WITH
PROBLEMSThe heater either does not switch on or automatically
switches off:
Insufficient fuel, fill up the fuel tank. Start up heater
several times, until the fuel lines are filled.
The auxiliary heater will automatically switch off if
the fuel level is under about 4 US gal (15 l).
The fuses in the fuse box are damaged. Electric
fuses.
The battery voltage is too low, an undervoltage
protector switches off the heater if the battery
voltage falls below about 10 volts.
The heater motor does not run
The battery voltage is too low, check the battery.
Batteries.
The fuses in the fuse box are damaged.
Electric fuses.
The heater motor is damaged.
Freightliner-all.book Pag e 130 Monday, December 1, 2003 2:54 PM
Page 133 of 272