For 1990-2009 cars

### HVAC Control - Automatic Climate Control

The operation of the automatic A/C and heating system is controlled by the buttons, rotary switch, and knobs on the HVAC control head. The compressor clutch, rear defog and recirc motor are controlled electrically by push buttons on the control head.

Blower speeds are controlled in all modes by a variable speed knob. The blower motor and compressor are not operational when the blower switch is in the OFF position.

The temperature knob controls the temperature door through an electric actuator, located on the left side of the HVAC module. The mode knob controls the various mode positions using an actuator, located on the right side of the HVAC module.

The control head logic will automatically select outside air and A/C whenever defrost and heater/defrost is selected, regardless of the A/C and recirculation button position.

Important: Anytime HVAC control head is removed and disconnected, control head will not display correct temperature information for approximately 5-10 minutes after reconnection.

### HVAC Module - Automatic Climate Control

The HVAC module consists of a recirc actuator, a mode actuator, blower motor and fan, a temperature door actuator, a blower motor control module, a heater core, and an evaporator core. The operations of these assemblies are controlled by the knobs and switches on the HVAC control panel.

Distribution of the air is controlled by the mode knob and buttons on the control assembly. The various positions of the mode knob and buttons direct cooled, heated, blended, outside, or inside air through the air ducts. The flow of air during the various modes of operations is as follows:

• | Face - Instrument panel outlets

• | Face and Feet - Instrument panel outlets and floor outlets

• | Feet - Floor outlets with a small amount of bleed air to defroster

• | Feet/Defrost - Floor outlets and defroster with slight bleed to instrument panel outlets

• | Top - Defroster ducts with small amount of air to side window defoggers

### Temperature Door Actuator - Automatic Climate Control

The temperature door actuator allows the operator to control the temperature of airflow into the passenger compartment. The temperature actuator rotates the mix door to open and close, which allows more air or less air to flow through the heater core.

### Blower Motor Control Module - Automatic Climate Control

The blower motor control module is located on the right side of the HVAC module near the front of dash. The control module lowers the blower motor voltage to create the speeds. The resistor card has a fusible link which if blown, will require that the card be replaced.

The blower motor will still operate in High when the fusible link is blown.

### Outside Air Temperature Sensor

The outside air temperature sensor provides a sample of outside air temperature. This signal is an input that tells the HVAC controller the outside air temperature. The controller uses information to adjust the inside air temperature of the vehicle.

### Solar Load Sensor

The solar load sensor is a light sensitive photodiode which senses ambient light levels in the vehicle. The HVAC module uses this information to compensate for the, green house, effect the sun has on the interior of the vehicle.