engine FORD MUSTANG 2003 Workshop Manual
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Page 3019 of 4378
PINPOINT TEST B: THE SET SPEED FLUCTUATES z
Is the resistance less than 5 ohms? A16 CHECK CIRCUIT 239 (WH/OG) FOR AN OPEN
z
Disconnect: PCM C175.
z Connect EEC- V 104-Pin Breakout Box.
z Measure the resistance between speed control servo C122 pin
3, circuit 239 (WH/OG), harness side and Breakout Box, EEC- V
Control System pin 68, circuit 239 (WH/OG), harness side.
z Is the resistance less than 5 ohms? Yes
GO to
A17 .
No
REPAIR the circuit.
TEST the system for
normal operation. A17 CHECK THE SPEED CONTROL SERVO
z
INSTALL a known good speed control servo.
z Test drive the vehicle for correct operation.
z Does the speed control operate correctly? Yes
INSTALL a new speed
control servo; REFER to
Actuator
— Speed
Control Servo . TEST
the system for normal
operation.
No
INSTALL a new PCM;
REFER to Section 303 -
14 . TEST the system
for normal operation. Test Step Result / Action to Take
B1 CHECK THAT CONDITION OCCURS
ONLY WHILE USING SPEED CONTROL z
Check that the condition does not occur
when driving without speed control.
z Does the condition occur without
speed control? Yes
REPAIR engine as necessary. TEST the
system for normal operation.
No
GO to
B2 . Klj . 9 ba
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DESCRIPTION AND OPERATION
Climate Control System
WARNING: To avoid accidental deployment and possible injury, the air bag system
backup power supply must be depleted before repairing any climate control components. To
deplete the backup power supply, disconnect the battery ground cable and wait one minute.
Failure to follow these instructions may result in personal injury.
WARNING: Carbon monoxide is colorless, odorless and dangerous. If it is necessary to
operate the engine with the vehicle in a closed area such as a garage, always use an exhaust
collector to vent the exhaust gases outside the closed area.
WARNING: R- 134a is classified as a safe refrigerant, but misuse can make it dangerous.
The following precautions must be observed:
zAlways wear safety goggles when repairing an air conditioning system.
z Avoid contact with liquid refrigerant R- 134a. R-134a vaporizes at approximately - 25°C (-
13°F) under atmospheric pressure and it will freeze skin tissue.
z Never allow refrigerant R- 134a gas to escape in quantity in an occupied space. R- 134a is
non- toxic, but it will displace the oxygen needed to support life.
z Never use a torch in an atmosphere containing R- 134a gas. R-134a is non-toxic at all
normal conditions, but when it is exposed to high temperatures, such as a torch flame, it
decomposes. During decomposition it releases irritation and toxic gases (as described in
the MSDS sheet from the manufacturer). Decomposition products are hydrofluoric acid,
carbon dioxide and water.
z Do not allow any portion of the charged air conditioning system to become too hot. The
pressure in an air conditioning system rises as the temperature rises and temperatures
of approximately 85°C (185°F) can be dangerous.
z Allow the engine to cool sufficiently prior to carrying out maintenance or serious burns
and injury can occur.
CAUTION: To avoid damaging the vehicle or A/C components, the following precautions
must be observed:
zThe A/C refrigerant of all vehicles must be identified and analyzed prior to refrigerant
charging. Failure to due so can contaminate the shop bulk refrigerant and other vehicles.
z Do not add R- 12 refrigerant to an A/C system that requires the use of R- 134a refrigerant.
These two types of refrigerant must never be mixed. Doing so can damage the A/C
system.
z Charge the A/C system with the engine running only at the low- pressure side to prevent
refrigerant slugging from damaging the A/C compressor.
z Use only R- 134a refrigerant. Due to environmental concerns, when the air conditioning
system is drained, the refrigerant must be collected using refrigerant recovery/recycling
equipment. Federal law REQUIRES that R- 134a be recovered into appropriate recovery
equipment and the process be conducted by qualified technicians who have been
certified by an approved organization, such as MACS, ASI etc. Use of a recovery machine
dedicated to R- 134a is necessary to reduce the possibility of oil and refrigerant
incompatibility concerns. Refer to the instructions provided by the equipment manufacturer when removing refrigerant from or charging the air conditioning system. SECTION 412-
00: Climate Control System - General Information 2003 Mustang Workshop Manual Klj . 1 ba
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If two substances of different temperature are placed near each other, the heat in the warmer
substance will transfer to the colder substance.
Latent Heat of Vaporization
When a liquid boils (converts to a gas), it absorbs heat without raising the temperature of the resulting
gas. When the gas condenses (reverts back to a liquid), it gives off heat without lowering the
temperature of the resulting liquid.
Relative Humidity
The amount of moisture (water vapor content) that the air can hold is directly related to the air
temperature. The more heat there is in the air, the more moisture the air can hold. The lower the
moisture content in the air, the more comfortable you feel. Removing moisture from the air lowers its
relative humidity and improves personal comfort.
Effects of Pressure on Boiling or Condensation
As the pressure is increased on a liquid, the temperature at which the liquid boils (converts to a gas)
also increases. Conversely, when the pressure on a liquid is reduced, its boiling point is also reduced.
When in the gas state, an increase in pressure causes an increase in temperature, while a decrease in
pressure will decrease the temperature of the gas.
Compressor Anti-
Slugging Strategy
Liquid refrigerant may accumulate in the A/C compressor under certain conditions. To alleviate
damage to the A/C compressor, compressor anti- slugging strategy (CASS) is utilized.
CASS is initiated only under specific conditions:
zthe ignition is off for more than 8 hours
z the ambient temperature is above -4º C (25ºF)
z battery voltage is above 8.5 volts during engine cranking
When these conditions are present, the powertrain control module (PCM) will activate the A/C control
relay prior to cranking of the engine. The A/C control relay engages the A/C compressor for
approximately 4- 15 A/C compressor revolutions or a maximum of 2 seconds (depending upon vehicle
application), allowing the liquid refrigerant to be pushed from the A/C compressor. CASS is initiated by
the PCM regardless of the function selector switch position or the EATC system settings.
The Refrigerant Cycle
During stabilized conditions (air conditioning system shut down), the refrigerant is in a vaporized state
and pressures are equal throughout the system. When the A/C compressor (19703) is in operation, it
increases pressure on the refrigerant vapor, raising its temperature. The high- pressure and high-
temperature vapor is then released into the top of the A/C condenser core (19712).
The A/C condenser core, being close to ambient temperature, causes the refrigerant vapor to
condense into a liquid when heat is removed from the refrigerant by ambient air passing over the fins
and tubing. The now liquid refrigerant, still at high pressure, exits from the bottom of the A/C
condenser core and enters the inlet side of the A/C evaporator core orifice (19D990).
The A/C evaporator core orifice is the restriction in the refrigerant system that creates the high
pressure buildup upstream of the A/C evaporator core (19860) and separates the high and low
pressure sides of the A/C system. As the liquid refrigerant leaves this restriction, its pressure and
boiling point are reduced.
The liquid refrigerant is now at its lowest pressure and temperature. As it passes through the A/C Klj . 3 ba
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Item Part Number Description
1 18A318 Vacuum control motor, panel/defrost door
2 18A478 Panel/defrost door (full vacuum position)
3 — Defrost airflow
4 — Side window demister airflow
5 18B545 Temperature blend door (full heat position)
6 19860 A/C evaporator core
7 19A813 Air inlet door (full vacuum position)
8 — Outside air inlet
9 18A318 Vacuum control motor—
air inlet door 10 — Recirculated air inlet
11 19805 Blower motor
12 — Vacuum from the engine intake manifold
13 19A563 A/C vacuum check valve
14 19A566 A/C vacuum reservoir tank and bracket
15 19B888 A/C-
heater function selector switch Klj . 3 ba
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2. Inspect to determine if one of the following mechanical or electrical concerns apply:
a A leak in the vacuum control circuit may occur during acceleration (slow leak), at all times
(large leak), or only when specific functions are selected (indicating a leak in that portion of the
circuit). The vacuum hoses used in the passenger compartment control circuit are constructed
from PVC plastic material. The vacuum hoses used in the engine compartment are constructed
of Hytrel® . Because of the materials used, never pinch the vacuum hoses off during diagnosis
to locate a leak. A wood golf tee can be used as a plug when it is necessary to plug one end of
a vacuum hose for leak test purposes.
3. If the inspection reveals obvious concerns that can be readily identified, repair as required.
4. If the concern remains after the inspection, connect the scan tool to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the scan
tool menu. If the vehicle selection cannot be entered:
zcheck that the program card is correctly installed.
z check the connections to the vehicle.
z check the ignition switch position.
If the scan tool still does not allow the vehicle selection to be entered, refer to the scan tool manual. 5. Carry out the DATA LINK DIAGNOSTIC TEST using the scan tool. If the scan tool responds with:
zCKT 914, CKT 915 or CKT 70 = ALL MODULE NO RESPONSE/NOT EQUIPPED, go to
Communication System Diagnostics in Section 418 - 00 to diagnose network concern.
z If the powertrain control module (PCM) is not listed for a communication concern, turn
the A/C function selector switch to OFF and execute self- test diagnostics for the PCM.
6. If any PCM DTCs are retrieved, and are related to the concern, go to the Powertrain Control Module Diagnostic Trouble Code (DTC) Index to continue diagnostics.
7. If no DTCs related to the concern are retrieved, go to the Symptom Chart to continue diagnostics.
Symptom Chart Visual Inspection Chart Mechanical Electrical
z
Loose, missing or damaged A/C compressor
drive belt.
z Loose or disconnected A/C clutch.
z Loose, misrouted or damaged vacuum lines. a
z Broken or leaking refrigerant lines.
z Broken or leaking vacuum control motor. z
Open fuses.
z Blower motor inoperative.
z A/C compressor inoperative.
z Circuitry open/shorted.
z Disconnected electrical
connectors.
Powertrain Control Module Diagnostic Trouble Code (DTC) Index DTC Description Action
P1460 WOT A/C cutout circuit
malfunction Refer to the Powertrain Control/Emissions Diagnosis
(PC/ED) manual.
P1464 A/C demand out of self-
test
range GO to DTC P1464. Klj . 5 ba
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Symptom Chart
Condition
Possible Sources Action
z Incorrect/erratic direction
of airflow from outlet(s) z
No vacuum to A/C heater
function switch selector.
z A/C heater function selector
switch leaks vacuum.
z Kinked/pinched vacuum hose.
z Leaking vacuum control
motor.
z Leaking A/C vacuum check
valve.
z Leaking A/C vacuum reservoir
tank and bracket.
z Vacuum actuator arm not
connected to door crank. z
Go To Pinpoint
Test A .
z Insufficient, erratic, or no
heat z
Low engine coolant level.
z Thermostat stuck open.
z Disengaged/damaged
temperature cable. z
Go To Pinpoint
Test B .
z The A/C does not
operate/does not operate
correctly z
CASS strategy failure.
z Open fuses.
z A/C clutch relay.
z Shorted blend door actuator.
z Powertrain control module.
z Circuitry short/open.
z A/C cycling switch damaged.
z A/C system discharged/low
charge.
z Function selector switch
damaged.
z A/C pressure cut-off switch
damaged.
z A/C compressor clutch
damaged. z
Go To Pinpoint
Test C .
z The A/C is always on zCircuitry short/open.
z A/C cycling switch.
z A/C heater function selector
switch.
z Constant control relay
module.
z Incorrect A/C clutch air gap. z
Go To Pinpoint
Test D .
z Insufficient A/C cooling zRestricted A/C evaporator
core orifice.
z Low refrigerant level. z
Go To Pinpoint
Test E .
z No operation in all the
temperature settings z
Damaged blend door actuator
cable.
z Damaged air temperature
control door. z
Go To Pinpoint
Test F .
z The blower motor does
not operate z
Open fuse.
z Circuitry open/shorted.
z Damaged heater blower
motor switch (18578).
z Damaged heater blower
motor switch resistor (18591).
z Damaged blower motor relay.
z Damaged blower motor. z
Go To Pinpoint
Test G .
z The blower motor
operates continuously in z
Circuitry short/open.
z Damaged heater blower z
Go To Pinpoint Klj . 6 ba
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PINPOINT TEST A: INCORRECT/ERRATIC DIRECTION OF AIRFLOW
FROM OUTLET z
Is there voltage present? Test Step Result / Action to
Take A1 CHECK AIRFLOW FROM DEFROSTER OUTLETS
z
Key in START position.
z Place the heater blower motor switch in the HI position and
rotate the function selector switch to each position.
z Check for correct airflow from each function selector switch
position at engine idle and during engine speed acceleration.
z Is there airflow from defroster outlets under all conditions? Yes
GO to
A2 .
No
If the airflow is from
defroster outlets in all
switch positions only
under engine speed
acceleration, GO to
A19 .
If the airflow is
incorrect under one or
more conditions, GO to
A13 .
If the airflow is correct
under all conditions,
RETURN to the
Symptom Chart. A2 CHECK THE VACUUM SUPPLY HOSE
z
Key in OFF position.
z Verify the vacuum supply hose is connected between the engine
manifold and the A/C vacuum check valve.
z Is the hose connected? Yes
GO to
A3 .
No
RECONNECT the
hose. TEST the system
for normal operation. A3 LEAK CHECK THE VACUUM SUPPLY HOSE Klj . 8 ba
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z
Disconnect: Vacuum Supply Hose.
z Connect one end of the vacuum supply hose to a vacuum pump
and test for leaks.
z Does the hose leak? Yes
REPAIR or INSTALL a
new vacuum hose.
TEST the system for
normal operation.
No
GO to
A4 .
A4 CHECK THE VACUUM CHECK VALVE
z
Key in START position.
z Check the A/C vacuum check valve for correct installation by
removing (one at a time) the reservoir hose and the control
assembly source hose from the A/C vacuum check valve. Check
for vacuum.
z Is vacuum available at both check valve ports? Yes
GO to
A6 .
No
GO to A5 .
A5 INSPECT THE VACUUM CHECK VALVE
z
Key in OFF position.
z Disconnect: A/C Vacuum Check Valve.
z Inspect the A/C vacuum check valve for an obstruction and
correct operation. Airflow through the A/C vacuum check valve
should be in the direction toward the engine (engine connection
site is marked "VAC").
z Is the A/C vacuum check valve plugged or obstructed? Yes
INSTALL a new A/C
vacuum check valve.
TEST the system for
normal operation.
No
GO to
A6 .
A6 LEAK TEST THE VACUUM CHECK VALVE
z
Key in OFF position.
z Disconnect: Vacuum Check Valve.
z Connect the A/C vacuum check valve to a vacuum pump with
two hoses and a tee fitting. Yes
INSTALL a new A/C
vacuum check valve.
TEST the system for
normal operation.
No
RECONNECT the A/C
vacuum check valve.
GO to
A7 . Klj . 9 ba
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PINPOINT TEST B: INSUFFICIENT, ERRATIC, OR NO HEAT z
Does the vacuum control motor hold a vacuum? A20 CHECK THE VACUUM CONTROL MOTOR INSTALLATION
z
Key in OFF position.
z Check the attachment of the vacuum control motor arm to
damper door.
z Is the vacuum control motor arm attached to the door or
door crank arm? Yes
REPAIR or INSTALL a
new damper door.
TEST the system for
normal operation.
No
CONNECT the vacuum
control motor arm to
the door and check
operation. TEST the
system for normal
operation.
Test Step Result / Action to Take
B1 CHECK FOR CORRECT ENGINE COOLANT LEVEL
z
Key in OFF position.
z Check the engine coolant level when hot and cold.
z Is the engine coolant at the correct level (hot/cold) as
indicated on the engine coolant recovery reservoir? Yes
GO to
B2 .
No
GO to B3 .
B2 CHECK FOR HOT WATER TO THE HEATER CORE INLET
HOSE WARNING: The heater core inlet hose will become
too hot to handle and may cause serious burns if the
system is working correctly.
z Key in START position.
z Allow the engine to reach normal operating temperature.
z Feel the heater core inlet hose. Yes
GO to
B4 .
No
TEST the engine cooling
system for correct
operation. REFER to
Section 303 - 03A or
Section 303 - 03B . Klj . 14 ba
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PINPOINT TEST C: THE A/C DOES NOT OPERATE/DOES NOT
OPERATE CORRECTLY z
Is the heater core inlet hose too hot to handle? B3 CHECK THE ENGINE COOLING SYSTEM INCLUDING
RADIATOR CAP FOR LEAKS z
Fill the engine cooling system to specified level.
z NOTE: It is not necessary to check the components
separately at this time.
z Pressure check the engine cooling system. Refer to Section 303 - 03A or
Section 303 - 03B .
z Does the engine cooling system, including the radiator
cap, hold pressure? Yes
GO to
B4 .
No
Pressure test the heater
core. REFER to
Component Tests, Heater
Core — Pressure Test. B4 CHECK THE HEATER CORE OUTLET HOSE FOR HOT
WATER z
Feel the heater core outlet hose.
z Is the heater core outlet hose cool or cold? Yes
TEST the heater core for a
plugged or partially
plugged condition. REFER
to
Section 303 - 03A or
Section 303 - 03B .
No
GO to Pinpoint Test E .
Test Step Result / Action to Take
C1 CHECK THE PCM PID WACF
z
Connect the diagnostic tool.
z Turn the function selector to the OFF position.
z Key in ON position.
z Enter the following diagnostic mode on the diagnostic
tool:
z Monitor the PCM PID WACF while turning the function
selector.
z Does the PCM PID WACF read YES? Yes
REFER to the Powertrain
Control/Emissions Diagnosis
(PC/ED) manual.
No
GO to
C2 .
C2 CHECK THE PCM PID WACF WITH THE A/C ON
z
Turn the function selector switch to the A/C position.
z Enter the following diagnostic mode on the diagnostic Yes
REFER to the Powertrain Klj . 15 ba
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