Fan Switch

The standard sleeper climate control panel has a fan switch and a temperature control switch with an A/C button.

If the bunk override button 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.

The fan switch activates the fan, which forces air through the air outlets. The fan switch has eight fan speeds and an OFF position. See Fig..

To operate the fan switch, turn the switch clockwise to increase airflow; turn the fan switch counterclockwise to decrease airflow. If the vehicle has Optimized Idle, the fan will not operate with the key in accessory mode. Optimized Idle may also turn the fan off to reduce stress on the batteries. Refer to Engine Protection—Warning and Shutdown for more information.

When the cab air conditioner (A/C) is on, the sleeper fan will operate at low speed even if the sleeper fan switch is in the off position. 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.

When the park brake is set, any temperature or blower speed setting changes on the bunk HVAC unit control panel will be mimicked by the front HVAC unit. For example, if you set bunk blower speed to HI and the temperature to COLD, the front unit will also operate on HI/COLD.

When the park brake is not set, the front and rear HVAC settings function independently, unless the bunk override button is pressed, or "minimum AC support" is required.

Minimum AC support is when the front unit is off and the bunk unit is set such that AC is requested (needs the AC compressor to run). In this case, the front unit will go into minimum AC support mode by operating the front blower at minimum speed to prevent the front unit evaporator from freezing up. This is also true, if the rear unit is off and the front unit is set such that AC is requested, in order to prevent the bunk evaporator from freezing up.