The various settings discussed in this section are used in order to provide comfortable heating or cooling. The heater and A/C programmer (1) directs 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 of the modes. The vents may be shut OFF by using the VENT dial located on the rear of the console. The air delivery mode is determined by the current or adjusted setting of the heater and A/C control.
Max A/C Mode
The maximum A/C mode is 16°C (60°F). Air is directed to the A/C outlets with bleed to the heater outlets. If AUTO is selected, the air inlet valve slowly opens providing 90% recirculated air. In ECON or OFF, the air inlet valve remains closed and provides only outside air.
A/C Mode
Air is directed to the A/C outlets with bleed airflow to the heater outlets. If previously in the AUTO-MAX A/C mode, the air inlet valve slowly closes in order to provide 100% outside air. The A/C clutch engages when the outside temperature is above 6°C (42°F) in order to help dehumidify the air.
Bi-Level Mode
During the bi-level mode, air is directed through the A/C and heater outlets. This mode is used as a transition between the heater mode and the A/C mode. The A/C clutch engages when the outside temperature is above 6°C (42°F) in order to help dehumidify the air.
Heater Mode
Air flow is directed to the heater outlets with bleed to the defrost outlets. The A/C clutch engages when the outside temperature is above 6°C (42°F) in order to help dehumidify the air.
Defog Mode
The defog mode splits the air between the heater (floor ducts) and the defroster. The A/C clutch engages when the outside temperature is above 6°C (42°F) in order to help dehumidify the air. The defog mode is enabled by pressing DEFOG on vehicles without D55 or by pressing the mode select button on vehicles with D55.
Off Mode
With the system OFF, the blower will remain OFF. Air is directed in the same manner as during the heater mode. The air mix valve controls the discharge air temperature.
Frost/Defrost Mode
Airflow is directed to the defroster outlets with bleed to the heater outlets. The system does not remember this mode after the driver turns OFF the key. 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 is above 36°C (97°F) for 3 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 volt limit does not apply.
IPC Cooling Mode
Under certain conditions, the blower will turn ON and will direct the air to the A/C vents in order to cool the instrument panel cluster (IPC). This prevents damage to the IPC electronic components. The IPC cooling mode is enabled under the following conditions:
| • | The ignition is in the RUN position. |
| • | The engine is not running or the heating, ventilation, and air conditioning (HVAC) is OFF. |
| • | The inside air temperature is greater than 51°C (125°F). |
| • | The blower-override modes are not operating. |
Once enabled, the minimum run time is 4 minutes. The IPC cooling mode is disabled under the following conditions:
| • | The inside air temperature is less than 50°C (121°F). |
| • | The engine is running and the HVAC is not OFF. |
| • | The engine is running. |
| • | Diagnostics are entered or a PCM-IPC Class 2 serial data fault is present. |
