Climate Control

Cab Climate Control Panel

The climate control panel allows the driver to control the heating, ventilating, defrosting, and air conditioning (A/C) functions. See Fig. 6.1 . The cab climate control panel has three knobs to control the functions of the cab temperature system:
fan control knob
air selection knob
temperature control knob
The climate control panel may also be equipped with up to three rocker switches to control recirculation, air conditioning, and bunk override.
  • 1. Bunk Override Switch
  • 2. Air Recirculation Switch
  • 3. Fan Control Knob
  • 4. Air Selection Knob
  • 5. Temperature Control Knob
Fig. 6.1, Cab Climate Control Panel
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 non-adjustable louvers. The bunk outlet (at the right-hand rear corner of the bunk) has two sets of vertical louvers that operate like the horizontal dash-face louvers.

Fan Control Knob

The fan control knob activates the fan, which forces fresh air or recirculated air through the air outlets. The fan control knob has eight fan speed settings and an OFF position.
To operate the fan knob, turn knob clockwise to increase airflow, or counterclockwise to decrease airflow.

Temperature Control Knob

The temperature control knob is used to select the desired temperature in the cab. Turn the knob counterclockwise for cool air, or clockwise for hot air.

Air Selection Knob

The air selection knob allows the driver to control the flow of air through the face outlets, the floor outlets, the defrost (windshield) outlets, or a combination of these outlets.
Air Conditioning Mode: Cools and dehumidifies the air inside the cab
Face Mode: Directs all airflow through the face or instrument panel outlets.
Bi-Level Mode: Directs the airflow equally to the face outlets and the floor outlets.
Floor Mode: Directs all airflow through the floor outlets.
Floor/Defrost Mode: Directs the airflow equally to the floor outlets and the defrost outlets.
Defrost Mode: Directs all airflow through the defrost outlets.
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.
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.

Recirculation Switch

When the recirculation switch is activated, the HVAC system limits the amount of outside air that enters the cab. Activate the recirculation switch to prevent dusty or smoky air from entering the cab. Recirculation mode can also decrease the time required to cool or heat the cab interior during extreme outside temperature conditions. When the recirculation mode is turned on, the amber indicator on the recirculation switch will illuminate.
The recirculation switch will not work when the mode control switch is in either defog or defrost modes.
IMPORTANT: 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 recirculation mode for more than 20 minutes.

Bunk Override Switch

The bunk override switch, equipped on sleeper cabs only, allows the driver to control sleeper heat and A/C settings from the cab. Press the bunk override switch to turn the sleeper heat or A/C on. An amber indicator will illuminate when bunk override mode is activated.
Press the bunk override switch again to turn bunk override mode off. Adjusting the sleeper climate controls at any time will also cause the bunk override mode to cancel.

Sleeper Climate Control Panel

An auxiliary heater and air conditioner unit is standard when there is a sleeper compartment. The unit is installed in the right side sleeper baggage compartment and uses the cab's refrigerant liquid 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. The auxiliary unit's climate control panel is mounted on the right rear wall or the rear overhead storage compartment.
The standard sleeper climate control panel has a fan control knob and a temperature control knob. See Fig. 6.2 .
  • 1. Clock
  • 2. Sound System Volume Knob
  • 3. Fan Control Knob
  • 4. Reading Light
  • 5. Temperature Control Knob
  • 6. Dome Light Switch
  • 7. Power Receptacle
Fig. 6.2, Sleeper Climate Control Panel
If the bunk override switch has been activated, the override mode can be canceled by changing the sleeper fan speed or temperature setting. The climate control system will then operate from the sleeper controls.
When the climate control unit is set for fresh air, 300 cubic feet per minute of air is provided to the sleeper and stale air is exhausted through a vent in the left rear area of the sleeper. When the system is activated, fresh air rapidly displaces stale air as the cab pressurizes.

Fan Control Knob

The fan control knob activates the fan, which forces air through the air outlets. The fan control knob has eight fan speeds and an OFF position.
To operate the fan control knob, turn the knob clockwise to increase airflow, or counterclockwise to decrease airflow.
IMPORTANT: To prevent the buildup of fumes or odors inside the sleeper (for example, from smoking) do not operate the heater and air conditioning system in recirculation mode for more than 20 minutes.
NOTE: When the cab air conditioner (A/C) is on, the sleeper fan will operate at low speed even if the sleeper fan knob is turned to OFF. This is necessary to protect the evaporator in the sleeper heater and air conditioner system from freezing. At lower fan speed settings, a slight increase in airflow levels may appear at times, as the control acts to regulate the evaporator temperature.

Temperature Control Knob

The temperature control knob is used to select the desired temperature in the sleeper. Turn the knob counterclockwise for cool air, or clockwise for hot air.