Door FORD MUSTANG 2003 Owner's Guide

DESCRIPTION AND OPERATION
Air Distribution
NOTE:
The air distribution system of this vehicle cannot be equipped with a cabin air filter.
There are two sources of air available to the air distribution system:
zoutside air
z recirculated air
Recirculated air is only used during MAX A/C.
Air distribution within the vehicle is determined by the function selector switch position. Airflow control
doors are used to direct airflow within the air plenum chamber. Vacuum control motors (18A318) are
used to position these airflow control doors. Refer to Section 412 - 00 for a description and operation of
each of the system functions.
The air distribution system is designed to provide airflow from the defrost nozzle when no vacuum is
applied to any of the vacuum control motors. This is done to prevent a situation where defrost cannot
be obtained due to a system vacuum leak.
Air enters the passenger compartment from the:
zinstrument panel A/C register (19893).
z heater outlet floor duct (18C433).
z windshield defroster hose nozzle (18490).
z side window demisters.
Passenger compartment air is exhausted from the vehicle through open windows or body air vents.
Instrument Panel Registers
There are A/C registers on the left and right sides of the instrument panel and in the center instrument
panel finish panel.
The LH and RH A/C registers are only serviceable as assemblies.
The center A/C registers are not serviceable as assemblies. The registers are installed with the
instrument panel center finish panel assembly. Component Locations SECTION 412-
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REMOVAL AND INSTALLATION
Door —
Air Inlet Duct
Removal 1. Remove the evaporator core housing. For additional information, refer to Section 412 - 02 .
2. Disconnect the vacuum line.
3. Remove the screws and remove the duct.
Installation 1. To install, reverse the removal procedure.
SECTION 412-
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DESCRIPTION AND OPERATION
Heating and Defrosting
The heating and defrosting system has the following features:
zControls the temperature and, during A/C operation, reduces the relative humidity of the air
inside the vehicle.
z Delivers heated or cooled air to maintain the vehicle interior temperature and comfort level.
z Controls the A/C blower motor speed.
z Cooling or heating can be adjusted to maintain the desired temperature.
z System uses a reheat method to provide conditioned air to the passenger compartment.
z The blower motor (19805) draws outside air through the air inlet duct from just below the
windshield during all system operations except for MAX A/C cooling (when recirculated air is
used).
z All airflow from the blower motor passes through the A/C evaporator core (19860).
z The temperature is then regulated by reheating a portion of the air and blending it with the
remaining cool air to the desired temperature.
z The temperature blending is varied by the air temperature control door, which regulates the
amount of air that flows through and around the heater core (18476), where it is then mixed and
distributed.
Heater Core
The heater core (18476) consists of fins and tubes arranged to extract heat from the engine coolant
and transfer it to air passing through the heater core. Blower Motor SECTION 412-
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6. Remove the heater air damper door motor.
1. Disconnect the vacuum lines.
2. Loosen the nuts and unclip the motor.
7. Release the vacuum harness from the housing.
8. Remove the screws and remove the resistor.
9. Disconnect the jumper wire. Klj . 2 ba
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Control System Inputs
Climate Control Assembly
The climate control assembly has three system controls:
zThe blower motor switch controls blower motor speed by adding or bypassing resistors in the
heater blower motor resistor.
z The temperature selection is accomplished with a manually- controlled blend door actuator that
controls positioning of the temperature blend door. Movement of the control knob (18519) from Item Part
Number Description
1 18A318 Vacuum control motor (panel/defrost door)
2 19988 Temperature blend door actuator cable
3 18A318 Vacuum control motor (air inlet door)
4 A/C vacuum reservoir tank and bracket (part of
18454)
5 18A318 Vacuum control motor (floor/panel door) Klj . 2 ba
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COOL (blue) to WARM (red) causes a corresponding movement on the air temperature control
door and determines the temperature that the system will maintain.
z The A/C heater function selector switch combines a vacuum selector valve for direct control of
the vacuum control motors and electrical input to the instrument control module.
Control System Outputs
Blower Motor Switch Resistor
The heater blower motor switch resistor has the following features:
zThe assembly is located on the passenger side of the plenum assembly behind the glove
compartment (06010).
z Three resistance elements are mounted on the resistor board to provide four A/C blower motor
speeds.
z Depending on the heater blower motor switch position, series resistance is added or bypassed
in the A/C blower motor circuit to decrease or increase A/C blower motor speed.
z An overheating protective device (thermal limiter) will open the resistor coil circuit when the
temperature reaches 105°- 110°C (221°-230°F), interrupting the blower motor operation in all
speeds except HI.
z The thermal limiter cannot be reset and is not serviceable.
Control Actuators
Temperature Control Cable
The temperature control cable (19988) has the following features:
zThe cable assembly has a constant tension (pull- pull) dual cable design.
z The pull- pull design allows for constant smooth communication between the temperature control
knob and the air temperature blend door.
z The control cable can only be installed as an assembly.
Vacuum Control Motors
The vacuum control motors (18A318) control the position of the doors directing the air flow to the
different outlets. There are two types of vacuum control motors used in this system:
zSingle- diaphragm for air inlet and windshield defroster door operations.
z Double- diaphragm for air damper door operations.
Single- diaphragm motors have two positions:
z Shaft extended with no vacuum applied.
z Shaft retracted with vacuum applied.
Double- diaphragm motors have three positions:
z Shaft extended with no vacuum applied to either port.
z Shaft halfway retracted with vacuum applied to only one port. Klj . 3 ba
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5. Remove the nuts and disconnect the vacuum connector.
Installation 1. Align the blend door driver to the full heat position.
2. Place the temperature control knob in the full WARM position.
3. Attach the cable drive to the control head. Klj . 2 ba
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REMOVAL AND INSTALLATION
Vacuum Control Motor —Air Inlet Duct Door
Removal 1. Remove the instrument panel. For additional information, refer to Section 501 - 12 .
2. Disconnect the vacuum hose.
3. Disconnect the control arm.
4. Remove the vacuum control motor. zRemove the screws.
Installation 1. To install, reverse the removal procedure.
SECTION 412-
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REMOVAL AND INSTALLATION
Vacuum Control Motor —Air Damper Door
Removal 1. Remove the instrument panel. For additional information, refer to Section 501 - 12 .
2. Disconnect the vacuum hose.
3. Remove the vacuum control motor. 1. Remove the steel clip.
2. Loosen the nuts.
Installation 1. To install, reverse the removal procedure.
SECTION 412-
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REMOVAL AND INSTALLATION
Vacuum Control Motor —Windshield/Defroster Door
Removal 1. Remove the instrument panel. For additional information, refer to Section 501 - 12 .
2. Unclip the control arm.
3. Remove the vacuum control motor. 1. Disconnect the vacuum lines.
2. Loosen the nuts.
Installation 1. To install, reverse the removal procedure.
SECTION 412-
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