Heater and Air Conditioner

HVAC General Information

A dash-mounted climate control panel ( Fig. 4.1 ) allows you to control all of the heating, air conditioning, defrosting, and ventilating functions.
A four-speed fan forces fresh or recirculated air to any selected air outlets at the windshield, door windows, dashboard face, and cab floor. See Fig. 4.2 .
All of the dash-face outlets have adjustable louvers that pivot right and left, and up and down. The outlets can be closed by moving the louvers all the way down. Windshield defrost outlets and the passenger's door window defrost outlet have nonadjustable louvers. The bunk outlet (on the right-hand wall of the bunk) has two sets of vertical louvers that operate like the horizontal dash-face louvers.
Fig. 4.1, Climate Control Panel
  • 1. Dash Face Outlet (driver's door window defrost outlet)
  • 2. Windshield Defrost Outlet
  • 3. Fresh Air Inlet
  • 4. Passenger's Door Window Defrost Outlet
  • 5. Dash Face Outlet
  • 6. Blower Motor
  • 7. Floor Outlet
  • 8. Recirculated Air Inlet
  • 9. Dash Face Outlet
Fig. 4.2, Air Outlet and Inlet System
An auxiliary heater and air conditioner unit is standard when there is a sleeper compartment. The unit is installed in the sleeper baggage compartment and uses the cab's refrigerant system for air conditioner operation. The unit is equipped with a separate evaporator coil, expansion valve, and fan. It is also equipped with its own heater core and water valve, independent of the cab heater. On vehicles with a 60-inch sleeper the auxiliary unit's climate control panel ( Fig. 4.3 or Fig. 4.4 ) is located in the shelf area; with a 40-inch sleeper it is mounted on the left front wall. On vehicles with a 48-inch or 70-inch SleeperCab, the control panel is mounted on the left rear wall or the rear overhead storage compartment.
Fig. 4.3, Control Panel for a Manual Temperature Control Cable System
Fig. 4.4, Control Panel for Automatic Temperature Control System
NOTE: Shutting off the heater supply gate valve (if equipped) on the engine limits the ability to control air conditioning temperature in the cab and in the sleeper. With the valve shut off, warm coolant is no longer available from the engine, and the outlet air temperature controls can't be used to change air temperature.
A FRESH/RECIRC push button ( Fig. 4.5 ) is standard equipment when there is no air conditioning. This control is an option when air conditioning is ordered. It allows the AC, VENT, and HEAT modes to be used with either fresh or recirculated air. When the mode control (upper lever) is at HEAT/DEF or DEF, the system draws in fresh air, regardless of the FRESH/RECIRC push button setting. When the mode control is at MAX A/C, the system draws only recirculated air, regardless of the FRESH/RECIRC push button setting. When the mode control is at A/C and the FRESH/RECIRC control is set for recirculation (push button in), the system functions the same as when the mode control is at MAX A/C. To prevent the buildup of fumes or odors inside the cab (for example, from smoking), do not operate the heater and air conditioning system in a recirculation mode for more than 20 minutes.
Fig. 4.5, FRESH/RECIRC Push Button

Defogging and Defrosting Using Fresh Air

1.
Set the mode control (upper lever) to HEAT, the fan switch to OFF and, if so equipped, the bunk fan switch to OFF before starting the engine. See Fig. 4.6 .
  • A. Fan Switch at Position 4
  • B. Mode Control at DEF
  • C. Temperature Control at WARM
Fig. 4.6, Settings for Defog/Defrost
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, slide the temperature control (lower lever) to WARM.
4.
Move the mode control to DEF. In this position the system is engaged to dehumidify the air before heating it, unless the temperature at the evaporator coil is less than 32°F (0°C). Warm, dry air is directed to the windshield.
IMPORTANT: If equipped with a FRESH/RECIRC push button, the system draws in fresh air when the mode control (upper lever) is at HEAT/DEF or DEF, regardless of the FRESH/RECIRC push button setting.
NOTE: At DEF, airflow is directed to the windshield outlets and the extreme left and right dash-face outlets. To defrost the driver's door window, turn the extreme left dash-face outlet to direct airflow to the upper left. In all positions of the mode control, airflow is directed to the passenger's door window.

Heating

1.
With the engine at operating temperature, set the mode control to HEAT. See Fig. 4.7 .
  • A. Fan Switch at Position 4 (or lower as desired)
  • B. Mode Control at HEAT
  • C. Temperature Control at WARM
Fig. 4.7, Settings for Maximum Heat
2.
Slide the temperature control to WARM.
3.
Turn on the fan switch to the desired speed.
IMPORTANT: If the windows start to fog, move the mode control to HEAT/DEF or DEF, and make sure the fan is on. To defog the driver's door window, turn the extreme left dash-face outlet to direct airflow to the upper left. In all positions of the mode control, airflow is directed to the passenger's door window.
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 with a rear climate control panel, set the controls as desired. For instructions, refer to "Heating, Auxiliary Heater and Air Conditioner."
5.
When a comfortable temperature has been reached, adjust the fan switch setting and temperature control as needed to maintain the temperature.
IMPORTANT: If equipped with a FRESH/RECIRC push button ( Fig. 4.5 ), the system draws in fresh air when the mode control (upper lever) is at HEAT/DEF or DEF, regardless of the FRESH/RECIRC push button setting. However, when the mode control lever is at HEAT, and the push button is in, the system draws only recirculated air. To prevent the buildup of fumes or odors inside the cab (for example, from smoking), do not operate the heater and air conditioning 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 system. Operate the air conditioner only after the engine compartment is warm, and the interior of the cab is 70°F (21°C) or higher. During cold weather, the heater can be operated at the same time, to prevent discomfort.
1.
If the cab is hot inside, temporarily open the windows to let the hot air out.
2.
Set the mode control to VENT and turn the fan switch off before starting the engine.
3.
Start the engine.
4.
Move the mode control to A/C. See Fig. 4.8 . With the control at A/C, fresh air is drawn into the cab. With the control at MAX A/C, the air inside the cab is recirculated.
  • A. Fan Switch at Position 4 (or lower as desired)
  • B. Mode Control at A/C
  • C. Temperature Control at COOL
Fig. 4.8, Settings for Cooling with A/C
IMPORTANT: If the outside air is dusty or smoky, set the mode control at MAX A/C and keep the windows and vent closed, to prevent drawing in dust or smoke. On vehicles with the FRESH/RECIRC push button, recirculated air can be selected either with the push button in or by setting the mode control to MAX A/C.
5.
Move the temperature control to COOL. In this position, no heat is given off by the heater.
6.
Turn the fan switch to the highest speed, 4.
7.
As soon as cool air is flowing from the dashboard outlets, close the windows. Adjust the fan switch setting as desired.
8.
If the air from the vents is too cold, move the temperature control toward WARM to adjust the temperature.
IMPORTANT: A FRESH/RECIRC push button ( Fig. 4.5 ) is standard equipment when there is no air conditioning. This control is an option when air conditioning is ordered. It allows the AC, VENT, and HEAT modes to be used with either fresh or recirculated air. When the mode control is at MAX A/C, the system draws only recirculated air, regardless of the FRESH/RECIRC push button setting. When the mode control is at A/C and the FRESH/RECIRC control is set for recirculation (push button in), the system functions the same as when the mode control is at MAX A/C. To prevent the buildup of fumes or odors inside the cab (for example, from smoking), do not operate the heater and air conditioning system in a recirculation mode for more than 20 minutes.
NOTE: The mode control must be at either A/C or MAX A/C, and the fan switch must be on for the air conditioning system to work.

Fresh Air

1.
Move the mode control to VENT or HEAT. See Fig. 4.9 . In the VENT position, air comes out of the dashboard outlets but not out of the floor outlets. In the HEAT position, air comes out of the floor outlets and the outlets on either end of the dashboard, but the center dashboard outlets are closed.
  • A. Fan Switch at Position OFF Through 4 as Desired
  • B. Mode Control at VENT or HEAT
  • C. Temperature Control at COOL
Fig. 4.9, Settings for Maximum Ventilation
2.
Set the temperature control to COOL for no heating, or move it toward WARM for heat.
3.
Set the fan switch at the desired speed.
IMPORTANT: If equipped with a FRESH/RECIRC push button ( Fig. 4.5 ), the system draws only recirculated air when the mode control lever is at VENT or HEAT, and the push button is in. To prevent the buildup of fumes or odors inside the cab (for example, from smoking), do not operate the heater or ventilation system in a recirculation mode for more than 20 minutes.

Heating, Sleeper Heater and Air Conditioner

1.
If equipped with the manual temperature control, do the following ( Fig. 4.10 ):
  • 1. Fan Control Knob
Fig. 4.10, Control Panel for Manual Temperature Control System
1.1
With the engine at operating temperature, pull the temperature control cable (attached to the outlet duct at the foot of the bunk) all the way out. Turn the fan control knob to position 3.
1.2
When the sleeper compartment heats to the desired temperature, push in the temperature control cable to adjust outlet air temperature. Then, turn the fan control knob to adjust the air flow level.
1.2
Use the manual temperature control and the fan control knob as needed to help maintain the desired temperature.
1.3
Whenever heat is not desired, push the temperature control cable all the way in, and turn off the fan.
2.
If equipped with either the Red Dot constant temperature control (CTC™) system, or the Behr automatic temperature control system ( Fig. 4.11 ), do the following:
  • 1. Temperature Rheostat
  • 2. Fan Control Knob
Fig. 4.11, Control Panel for Automatic Temperature Control System
2.1
With the engine at operating temperature, turn the rotary knob on the temperature rheostat all the way clockwise to HEAT. Turn the fan control knob to position 3.
2.2
When the sleeper compartment heats to the desired temperature, turn the rotary knob on the temperature rheostat counterclockwise to adjust outlet air temperature. Then, turn the fan control knob to adjust the air flow level.
2.2
The system will automatically maintain the selected outlet air temperature.
2.3
Whenever heat is not desired, turn the rotary knob on the temperature rheostat counterclockwise (as needed) and turn off the fan.

Air Conditioning, Sleeper Heater and Air Conditioner

1.
If equipped with the manual temperature control, do the following:
1.1
Turn on the cab air conditioner. For instructions, refer to "Air Conditioning."
1.2
Make sure that the temperature control cable (attached to the outlet duct at the foot of the bunk) is pushed in all the way. Turn the fan control knob to position 3.
1.3
When the sleeper compartment cools to the desired temperature, turn the fan control knob to adjust the air flow level. If needed, pull the temperature control cable out to adjust outlet air temperature. Use the temperature control cable and the fan control knob as needed to help maintain the desired temperature.
1.4
Whenever air conditioning is not desired, pull the temperature control cable out (as needed) and turn off the fan.
NOTE: Whenever the refrigerant compressor is operating, the fan will always run at a very low speed, even with the fan control knob in the "Off" position. This prevents ice from forming on the evaporator, especially during humid weather.
2.
If equipped with either the Red Dot constant temperature control (CTC™) system, or the Behr automatic temperature control system, do the following:
2.1
Turn on the cab air conditioner. For instructions, refer to "Air Conditioning."
2.2
Turn the rotary knob on the temperature rheostat all the way counterclockwise to COOL. Turn the fan control knob to position 3.
2.3
When the sleeper compartment cools to the desired temperature, turn the rotary knob on the temperature rheostat clockwise to adjust outlet air temperature. Then, turn the fan control knob to adjust the air flow level.
2.3
The system will automatically maintain the selected outlet air temperature.
2.4
Whenever air conditioning is not desired, turn the rotary knob on the temperature rheostat clockwise (as needed) and turn off the fan.
NOTE: Whenever the refrigerant compressor is operating, the fan will always run at a very low speed, even with the fan control knob in the "Off" position. This prevents ice from forming on the evaporator, especially during humid weather.