Air Delivery Mode Control

Mode Valves:

The various settings discussed in this section are used to provide comfortable heating or cooling. The heater and A/C programmer will direct the blended air in one of several air delivery modes. The side window outlets receive airflow during all modes of operation. The rear air outlets receive airflow during all modes as well; however, the vents may be shut OFF if desired by the VENT dial located on the rear of the console. Based on the current program number and control center setting the heater and A/C programmer determines the air delivery mode. The following delivery modes are possible.

Max A/C Mode

The maximum A/C mode is 16°C (60°F). Air is distributed to the A/C outlets with bleed to heater outlets. Air inlet valve slowly opens if AUTO is selected which provides 90% recirculated air. In ECON or OFF, this valve will remain closed and provide only outside air.

A/C Mode

Air is delivered to the A/C outlets with bleed airflow to the heater outlets. If previously in AUTO-MAX A/C mode, air inlet valve will slowly close to provide 100% outside air. The A/C clutch is enabled if outside temperature is above 6°C (42°F) to help dehumidify the interior.

Bi-Level Mode

Air is dispensed through the A/C outlets and heater outlets. This mode is used to transition from A/C to heater mode or heater mode to A/C mode. The A/C clutch is enabled if outside temperature is above 6°C (42°F) to help dehumidify the interior.

Heater Mode

Air flow is delivered by the heater outlets with bleed to defrost outlets. The A/C clutch is enabled if outside temperature is above 6°C (42°F) to help dehumidify the interior.

Defog Mode

This mode splits the air between the heater (floor ducts) and defrost&. The A/C clutch is enabled if outside temperature is above 6°C (42°F) to help dehumidify the interior.

This mode can be entered manually by pressing the DEFOG button on vehicles without D55. Vehicles equipped with the D55, DEFOG can be selected by pressing the mode select button.

Off Mode

With the system OFF, the blower will remain OFF Any air which enters as the vehicle is moving will be directed in the same manner as during the heater mode. The discharge air temperature will continue to be controlled by the air mix valve.

Front Defrost Mode

Airflow is sent to the defroster outlets with bleed to heater outlets. This mode is not remembered after the key is turned OFF. The system will switch to the AUTO selection if FT DEF was previously active. If the operator selects FT DEF while the ambient temperature is below -4°C (25°F), the heater and A/C programmer will limit the blower to 7 volts until the coolant has been above 36°C (97°F) for three minutes This low blower voltage reduces the possibility of drawing snow through the air inlet. If the operator selects HI FAN while in this mode, the 7 volts blower limit will be overridden.

IPC Cooling Mode

Under certain conditions, the blower will turn ON and direct air to the A/C vents to cool the instrument panel cluster (IPC) to prevent damage to IPC electronic components. IPC cooling mode will be enabled with:

^ Ignition in RUN position.
^ Engine is not running or HVAC OFF.
^ Inside air temperature greater than 51°C (125°F).
^ Blower override modes are not operating.

Once enabled, minimum run time is four minutes. IPC cooling mode is disabled if:

^ Inside air temperature is less than 50°C (121°F) or engine is running and HVAC is not OFF
^ Engine is running.
^ Diagnostics is entered or a PCM-IPC Class 2 Serial Data fault is present.