Mode Control

Chevrolet:

Pontiac:

Mode Control Knob

The mode control knob is located on the right side of the HVAC control head. The following are the eight different modes to choose from:

^ OFF
^ MAX
^ A/C
^ BI-LEVEL A/C
^ VENT
^ HEATER
^ DEFROST/BLEND
^ DEFROST

The symbols are identified in the illustrations. Each setting is described below.

OFF

At this setting, there is no electrical power suppled to the blower motor and there is no A/C request signal sent to the powertrain control module (PCM). A small amount of air which is forced into the HVAC module by the forward movement of the vehicle will still be discharged through the heater and defrost outlets. This is the only setting in which the blower motor does not operate.

MAX

This setting is one of five settings in which there is a A/C request signal sent to the PCM. The blower motor will operate in one of four blower motor speed control settings and air will be discharged from the instrument panel air outlets only.

To provide MAX A/C, most of the air entering the HVAC module is taken from the vehicle interior (re-circulated) where it is most likely cooler than the outside air. This is the only setting in which air is re-circulated, all other settings use outside air only. This setting would be most useful during conditions of high temperature and humidity, or when the outside air may have an objectional odor

A/C

This setting functions the same as the MAX setting, except only outside air enters the HVAC module. There may be a slight reduction of blower noise compared to the MAX setting because the re-circulation valve (door) is closed.

BI-LEVEL A/C

At this setting a A/C request signal is sent to the PCM and allows the blower motor to operate in one of four settings. Only outside air enters the HVAC module and air is distributed through the instrument panel outlets and the floor outlets with a small amount to the defrost outlet.

VENT

This setting does not activate an A/C request signal but allows the blower motor to operate normally. This is one of two economy settings (other than OFF) in which there is not A/C request signal. Air is discharged through the instrument panel outlets only.

HEATER

This setting functions the same as the VENT setting, except that most of the air is discharged through the floor outlets with a small amount discharged through the defroster outlets. The HEATER setting is the normal selection for cold weather operation unless windshield or side window defogging/defrosting is required.

DEFROST/BLEND

This setting allows operation of the blower motor and activates an A/C request signal that is sent to the PCM. During this setting, air is discharged through the defroster and floor air outlets. This setting allows greater passenger comfort than the DEFROST setting but is not as effective in defogging/defrosting the windshield and side windows.

DEFROST

This setting functions the same as the DEFROST/BLEND setting except most of the air is discharged through the defroster outlets with a small amount going through the heater and side window defoggers.