2003 FORD MUSTANG key

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
412003 Mustang Workshop Manual
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z
Does the vacuum drop? system for normal
operation.
No
REPAIR or INSTALL a
new function selector
switch. TEST the
system for normal
operation.
A13 REVIEW THE VEHICLE'S HISTORY
z
Key in OFF position.
z Review the vehicles history.
z Did the climate control system function correctly prior to
this concern? Yes
GO to
A16 .
No
GO to A14 .
A14 CHECK THE VACUUM HOSES TO DAMPER DOORS
z
Connect a vacuum pump to each hose and try to pull a vacuum.
If the vacuum pump can pull a vacuum, the hose is plugged. If
the vacuum pump pulls a partial vacuum, the hose is restricted.
z Is a hose plugged or restricted? Yes
INSTALL a new
vacuum hose. TEST
the system for normal
operation.
No
GO to
A15 .
A15 CHECK THE VACUUM HARNESS
z
Compare the vacuum hose color in each vacuum harness to the
vacuum diagram.
z Does the hose color agree with the schematics? Yes
GO to
A16 .
No
INSTALL a new
vacuum harness. TEST
the system for normal
operation. A16 CHECK A/C VACUUM CIRCUIT
z
Check the A/C vacuum circuit for pinched or kinked vacuum
hose. Yes
REPAIR or INSTALL a
new vacuum hose.
TEST the system for
normal operation.
No
GO to
A17 . Klj . 12 ba
412003 Mustang Workshop Manual
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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
412003 Mustang Workshop Manual
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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
412003 Mustang Workshop Manual
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tool:
z Monitor the PCM PID WACF while turning the function
selector.
z Does the PCM PID WACF read YES? Control/Emissions Diagnosis
(PC/ED) manual.
No
GO to
C3 .
C3 CHECK THE PCM PID ACCS WITH THE A/C ON
z
Key in START position.
z Make sure the engine is at idle.
z Enter the following diagnostic mode on the diagnostic
tool: PCM PID ACCS.
z Monitor the PCM PID ACCS while turning the function
selector.
z Does the PCM PID ACCS read ON? Yes
GO to
C4 .
No
GO to C6 .
C4 CHECK PCM PID WAC WITH THE A/C ON
NOTE:
When PCM PID WACF is YES, this is the same
fault as DTC P1460.
z Enter the following diagnostic mode on the diagnostic
tool: PCM PID WAC.
z Monitor the PCM PID WAC while turning the function
selector.
z Does the PCM PID WAC read ON? Yes
GO to
C20 .
No
GO to C5 .
C5 CHECK THE INPUT SIGNAL TO THE PCM
z
Key in OFF position.
z Disconnect: PCM C175.
z Key in ON position.
z Measure the voltage at PCM C175- 41, circuit 198
(DG/OG), harness side and ground.
z Is the voltage reading greater than 10 volts? Yes
INSTALL a new powertrain
control module. TEST the
system for normal operation.
No
GO to
C6 .
C6 CHECK THE REFRIGERANT PRESSURE
z
Key in OFF position.
z Connect the manifold gauge set. Refer to Refrigerant System Tests in this section.
z Is the system pressure 345- 1,724kPa (50-250psi)? Yes
GO to
C7 .
No
REPAIR the leaks and
RETEST the system for normal
operation. REFER to Section 412 - 03 .
C7 CHECK THE SUPPLY TO THE FUNCTION SELECTOR
SWITCH z
Key in OFF position.
z Disconnect: Function Selector Switch C294c.
z Key in ON position.
z Measure the voltage at the function selector switch
C294c- 2, circuit 883 (PK/LB), harness side and ground. Yes
GO to
C17 .
No
GO to C8 . Klj . 16 ba
412003 Mustang Workshop Manual
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z
Is the voltage reading greater than 10 volts? C8 CHECK CIRCUIT 883 (PK/LB) FOR A SHORT TO
GROUND z
Key in OFF position.
z Measure the resistance between the function selector
switch C294c- 2, circuit 883 (PK/ LB) harness side and
ground.
z Is the resistance less than 5 ohms? Yes
GO to
C9 .
No
GO to C11 .
C9 CHECK CIRCUIT 348 (VT) FOR SHORT TO GROUND
z
Disconnect: A/C Cycling Switch C130.
z Measure the resistance between the function selector
switch C294c- 4, circuit 348 (VT) harness side and
ground.
z Is the resistance reading less than 10,000 ohms? Yes
REPAIR circuit 348 (VT). TEST
the system for normal
operation.
No
GO to
C10 .
C10 CHECK FOR A SHORTED FUNCTION SELECTOR
SWITCH z
Connect: Function Selector Switch C294c.
z Measure the resistance between the A/C cycling switch
C130- 4, circuit 348 (VT) harness side and ground. Yes
INSTALL a new function
selector switch. REFER to
Section 412
- 04 . TEST the
system for normal operation.
No
GO to C13 . Klj . 17 ba
412003 Mustang Workshop Manual
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z
Is the resistance reading less than 10,000 ohms? C13 CHECK CIRCUIT 198 (DG/OG) FOR A SHORT TO
GROUND z
Connect: A/C Pressure Cut- off Switch C1078.
z Measure the resistance between PCM C175- 41, circuit
198 (DG/OG), harness side and ground.
z Is the resistance less than 10,000 ohms? Yes
GO to
C15 .
No
INSTALL a new A/C fuse (15A).
TEST the system for normal
operation. If the fuse opens,
install a new PCM. REFER to
the Powertrain
Control/Emissions Diagnosis
(PC/ED) manual. C14 CHECK THE A/C PRESSURE CUT-
OFF SWITCH z
Disconnect: A/C Pressure Cut-off Switch C1078.
z Measure the resistance between the Rotunda EEC- V
Breakout Box pin 41, circuit 198 (DG/OG), and ground.
z Is the resistance less than 10,000 ohms? Yes
REPAIR circuit 198 (DG/OG)
for a short to ground. TEST the
system for normal operation.
No
INSTALL a new A/C pressure
cut-
off switch. REFER to
Section 412 - 03 .
C15 CHECK THE FUNCTION SELECTOR SWITCH
z
Key in OFF position.
z Connect: Function Selector Switch C294c.
z Disconnect: A/C Cycling Switch C130.
z Key in ON position.
z Turn the function selector switch to the A/C position.
z Measure the voltage between C130- 4, circuit 348 (VT),
harness side and ground. Yes
GO to
C17 .
No
GO to C16 . Klj . 19 ba
412003 Mustang Workshop Manual
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z
Is the voltage reading greater than 10 volts? C16 MEASURE THE RESISTANCE OF CIRCUIT 348 (VT)
z
Key in OFF position.
z Disconnect: Function Selector Switch C294c.
z Measure the resistance between the A/C function
selector switch C294c- 1, circuit 348 (VT), harness side
and A/C cycling switch C130- 4, circuit 348 (VT), harness
side.
z Is the resistance reading less than 5 ohms? Yes
INSTALL a new function
selector switch. REFER to
Section 412
- 04 . TEST the
system for normal operation.
No
REPAIR circuit 348 (VT) for an
open. TEST the system for
normal operation. C17 MEASURE THE VOLTAGE TO THE A/C PRESSURE
CUT- OFF SWITCH z
Key in OFF position.
z Connect: A/C Cycling Switch C130.
z Disconnect: A/C Pressure Cut-off Switch C1078.
z Turn the function selector switch to the A/C position.
z NOTE: The A/C pressure cut- off switch C1078 for the
3.8L engine is shown, C1078 for the 4.6L engines is
similar. The pin locations and the circuits are identical.
z Measure the voltage at the A/C high pressure cut- off
switch C1078- 2 circuit 420 (DB/YE), harness side and
ground. Yes
GO to
C19 .
No
GO to C18 . Klj . 20 ba
412003 Mustang Workshop Manual
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