The air temperature and the air delivery description and operation are divided into five areas:
HVAC Control Assembly
The HVAC control assembly interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The air temperature and mode doors are controlled by cables. The recirculation actuator is electrically controlled.
There are two different HVAC control assemblies. The first type uses serial data to communicate system messages and requests to other module. The other uses discrete hard–wired signals to communicate commands. The hard–wired HVAC control assembly cannot communicate via serial data.
HVAC control module programming can not be performed on the hard–wired HVAC control assembly.
The HVAC control module supports the following features:
Feature |
Availability |
---|---|
Afterblow |
NO |
Purge |
NO |
Personalization |
NO |
Actuator Calibration |
NO |
Evaporator Temperature Sensor
The evaporator temperature sensor is a two-wire negative temperature co-efficient thermistor. The sensor operates within a temperature range of -40 to +85°C (-40 to +185°F). The sensor is installed at the evaporator and measures its temperature. If the temperature drops under 1°C (34°F), the compressor will be switched off in order to prevent a frozen evaporator.
A/C Refrigerant Pressure Sensor
The engine control module (ECM) monitors the high side refrigerant pressure through the A/C refrigerant pressure sensor. The ECM supplies a 5V reference and a low reference to the sensor. Changes in the A/C refrigerant pressure cause the sensor signal to the ECM to vary. When the pressure is high, the signal voltage is high. When the pressure is low, the signal voltage is low. When pressure is high, the ECM commands the cooling fans on. When pressure is too high or too low, the ECM will inhibit activation of the A/C compressor.
A/C Compressor
The A/C compressor is belt driven and operates when the magnetic clutch is engaged. When the A/C switch is pressed, an A/C request message to the ECM. If the ECM determines that conditions are acceptable for A/C operation, it will ground the A/C compressor clutch relay control circuit, which activate the A/C compressor clutch relay. With the relay contacts closed, battery voltage is supplied to the A/C compressor clutch. The A/C compressor clutch will engage and the compressor will operate.
The HVAC control assembly applies a ground to the blower motor control circuit that corresponds to the selected blower speed. The resistors and the blower motor are in a series circuit. The following list represents the number of resistors in series with the blower motor per particular speed request:
When blower switch is in the Hi speed position, ground is applied directly to the blower motor through the blower switch.
The HVAC control assembly controls the distribution of air by the use of recirculation actuator and the mechanically controlled mode door. The modes that may be selected are:
The desired air distribution mode can be selected with the air distribution knob at the HVAC control assembly. Depending on the position of the flap, air is distributed through various ducts leading to the outlets in the instrument panel. When the defrost position is selected, the HVAC control assembly will command the recirculation actuator to outside air, reducing window fogging.
The purpose of the heating and A/C system is to provide heated and cooled air to the interior of the vehicle. The A/C system will also remove humidity from the interior and reduce windshield fogging. Regardless of the temperature setting, the following can affect the rate that the HVAC system can achieve the desired temperature:
When the A/C switch is pressed, an A/C request message to the ECM. If the ECM determines that conditions are acceptable for A/C operation, it will ground the A/C compressor clutch relay control circuit, which activate the A/C compressor clutch relay. With the relay contacts closed, battery voltage is supplied to the A/C compressor clutch. The A/C compressor clutch will engage and the compressor will operate.
The following conditions must be met in order to activate the A/C compressor:
The temperature door controls the temperature of the air entering the passenger compartment. Air entering the passenger compartment passes through the heater core and/or the evaporator core. The position of the temperature door determines how much air passes through the heater or evaporator core. As the temperature control is moved to a hotter setting, the temperature door will direct more air through the heater core. As the temperature control is moved to a cooler setting, more air will be passed through the evaporator core.
Recirculation Actuator
The recirculation actuator is a two-wire bi-directional electric motor. There are two control circuits that allow actuator operation. The control circuits use either a 0 or 12-volt value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 volts.To move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction.
Instrument Panel Outer Trim Cover Replacement
Instrument Panel Outer Trim Cover Replacement
Callout
Component Name
1
Instrument Panel Outer Trim Cover (Qty:?€‰2)
Procedures
Use a flat bladed plastic trim tool in order to disengage the retainers
securi ...
Sunroof Switch Replacement
Sunroof Switch Replacement
Callout
Component Name
Preliminary Procedure
Remove the dome lamp bezel. Refer to Dome Lamp Bezel Replacement.
1
Sunroof Switch
Procedure
Disconnect electrical conn ...
Transmission Fluid Level and Condition Check
Removal Procedure
Raise and support the vehicle. Refer to
Lifting and Jacking the Vehicle
Remove the front suspension skid plate, if equipped.
Refer to Drivetrain and Front Suspension Frame Skid
Plate Replacement
Place a basin underneath the vehicle.
Clean away all ...