Ford Mustang (1999-2004) Service Manual: Pinpoint Tests

PINPOINT TEST P1464: DTC P1464: A/C DEMAND OUT OF SELFTEST RANGE

Test Step	Result / Action to Take
P14641 RECHECK FOR THE DTC	Yes GO to P14642 . No The system is functioning correctly. This DTC will set if the A/C is turned on when carrying out the PCM self-test.
Key in ON position. Make sure the function selector switch is in the OFF position. Enter the following diagnostic mode on the diagnostic tool: PCM Self-Test. Is DTC P1464 retrieved?
P14642 CHECK PID ACCS WITH THE A/C CONTROL DISCONNECTED	Yes GO to P14643 . No INSTALL a new function selector switch. REFER to Section. REPEAT the PCM self-test and verify DTC P1464 is no longer retrieved.
Key in OFF position. Disconnect: Function Selector Switch C294c. Key in ON position. Enter the following diagnostic mode on the diagnostic tool: PCM PID ACCS. Does PID ACCS read ON?
P14643 CHECK CIRCUIT 348 (VT) FOR A SHORT TO B+	Yes REPAIR circuit 348 (VT ) for a short to B+. REPEAT the PCM self-test and verify DTC P1464 is no longer retrieved. No INSTALL a new powertrain control module. REFER to Section. REPEAT the PCM self-test and verify DTC P1464 is no longer retrieved.
Key in OFF position. Disconnect: PCM C175. Key in ON position. Measure the voltage at the function selector switch C294c-4, circuit 348 (VT), the harness side and ground. Is there voltage present?

PINPOINT TEST A: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET

Test Step

Result / Action to Take

A1 CHECK AIRFLOW FROM DEFROSTER OUTLETS

Yes

GO to A2 .

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.

Key in START position.
Place the heater blower motor switch in the HI position and rotate the function selector switch to each position.
Check for correct airflow from each function selector switch position at engine idle and during engine speed acceleration.
Is there airflow from defroster outlets under all conditions?

A2 CHECK THE VACUUM SUPPLY HOSE

Yes

GO to A3 .

RECONNECT the hose. TEST the system for normal operation.

Key in OFF position.
Verify the vacuum supply hose is connected between the engine manifold and the A/C vacuum check valve.

Is the hose connected?

A3 LEAK CHECK THE VACUUM SUPPLY HOSE

Yes

REPAIR or INSTALL a new vacuum hose.

TEST the system for normal operation.

GO to A4 .

Disconnect: Vacuum Supply Hose.
Connect one end of the vacuum supply hose to a vacuum pump and test for leaks.

Does the hose leak?

A4 CHECK THE VACUUM CHECK VALVE

Yes

GO to A6 .

GO to A5 .

Key in START position.
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.

Is vacuum available at both check valve ports?

A5 INSPECT THE VACUUM CHECK VALVE

Yes

INSTALL a new A/C vacuum check valve.

TEST the system for normal operation.

GO to A6 .

Key in OFF position.
Disconnect: A/C Vacuum Check Valve.
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").
Is the A/C vacuum check valve plugged or obstructed?

A6 LEAK TEST THE VACUUM CHECK VALVE

Yes

INSTALL a new A/C vacuum check valve.

TEST the system for normal operation.

RECONNECT the A/C vacuum check valve.

GO to A7 .

Key in OFF position.
Disconnect: Vacuum Check Valve.
Connect the A/C vacuum check valve to a vacuum pump with two hoses and a tee fitting.

Pump 51 kPa (15 in-Hg) vacuum on the A/C vacuum check valve and observe the gauge reading.
If the vacuum loss exceeds 3.37 kPa (1 in-Hg) per minute, remove the A/C vacuum check valve from the tester and plug the vacuum hoses. Pump 51 kPa (15 in-Hg) of vacuum with the tester to be certain the hoses and tester are not the cause of the leak.

Does the A/C vacuum check valve lose more than 3.37 kPa (1 in-Hg) of vacuum in one minute?

A7 CHECK THE VACUUM RESERVOIR

Yes

INSTALL a new A/C vacuum reservoir tank.

TEST the system for normal operation.

RECONNECT the A/C vacuum reservoir tank.

GO to A8 .

Disconnect: A/C Vacuum Reservoir Tank.
Use a vacuum pump to leak test the A/C vacuum reservoir tank.

Does the reservoir leak?

A8 CHECK THE SUPPLY HOSE

Yes

REPAIR or INSTALL a new function selector switch supply hose.

TEST the system for normal operation.

RECONNECT the function selector switch supply hose. GO to A9 .

Disconnect: Function Selector Switch Supply Hose.
Use a vacuum pump to leak test the function selector switch supply hose.

Does the function selector switch supply hose leak?

A9 CHECK THE CONTROL ASSEMBLY

Yes

NOTE the function selector switch position where the vacuum drops. GO to A10 .

RECONNECT the inline vacuum harness connector. GO to A11 .

Disconnect: In-line Vacuum Harness.
Connect a vacuum pump to the black hose and plug the other hoses.

At each function selector switch position, apply 51 kPa (15 in-Hg) of vacuum and check for vacuum drop.
Does the vacuum drop exceed 3.37 kPa (1 in-Hg) per minute?

A10 LEAK TEST THE CONTROL ASSEMBLY

Yes

INSTALL a new function selector switch. TEST the system for normal operation.

RECONNECT the function selector switch vacuum connector. GO to A12 .

Disconnect: Function Selector Switch Vacuum.
Connect a vacuum pump to the function selector switch supply port and plug the control port that indicated a leak in Step A9.

Select the function selector switch position that indicated a leak in Step A9 and then apply 51 kPa (15 in-Hg) of vacuum.
Does the vacuum drop exceed 1.68 kPa (0.5 in-Hg) per minute?

A11 CHECK THE SUPPLY HOSE FOR OBSTRUCTIONS

Yes

INSTALL a new supply hose. TEST the system for normal operation.

RECONNECT the A/C damper door switch supply hose. GO to A15 .

Disconnect: Mode Selector Switch Supply Hose.
Connect a vacuum pump to the supply 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.

Is the hose plugged or restricted?

A12 LEAK TEST THE JUMPER VACUUM HARNESS

Yes

REPAIR or INSTALL a new vacuum jumper harness. TEST the system for normal operation.

REPAIR or INSTALL a new function selector switch. TEST the system for normal operation.

Disconnect:
Disconnect the suspect hose.
Plug one end of the suspect hose and attach a vacuum pump to the other end. Apply 51 kPa (15 in-Hg) of vacuum to the hose.

Does the vacuum drop?

A13 REVIEW THE VEHICLE'S HISTORY

Yes

GO to A16 .

GO to A14 .

Key in OFF position.
Review the vehicles history.
Did the climate control system function correctly prior to this concern?

A14 CHECK THE VACUUM HOSES TO DAMPER DOORS

Yes

INSTALL a new vacuum hose. TEST the system for normal operation.

GO to A15 .

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.

Is a hose plugged or restricted?

A15 CHECK THE VACUUM HARNESS

Yes

GO to A16 .

INSTALL a new vacuum harness. TEST the system for normal operation.

Compare the vacuum hose color in each vacuum harness to the vacuum diagram.
Does the hose color agree with the schematics?

A16 CHECK A/C VACUUM CIRCUIT

Yes

REPAIR or INSTALL a new vacuum hose.

TEST the system for normal operation.

GO to A17 .

Check the A/C vacuum circuit for pinched or kinked vacuum hose.

Is the hose pinched or kinked?

A17 CHECK VACUUM CIRCUIT CONNECTIONS

Yes

RECONNECT the hose. TEST the system for normal operation.

GO to A18 .

Check each vacuum hose connection to determine if it is partially connected or disconnected

Is a vacuum hose disconnected or partially connected?

A18 CHECK THE VACUUM HOSE

Yes

REPAIR or INSTALL a new hose. TEST the system for normal operation.

GO to A19 .

Disconnect the suspect hose.
Plug one end of the hose and attach a vacuum pump to the other end. Check for a leak in the hose.

Does the vacuum hose leak?

A19 CHECK THE VACUUM CONTROL MOTOR

Yes

GO to A20 .

INSTALL a new vacuum control motor.

TEST the system for normal operation.

Disconnect: Vacuum Control Motor.
Check the vacuum control motor for leaks with a vacuum pump.

Does the vacuum control motor hold a vacuum?

A20 CHECK THE VACUUM CONTROL MOTOR INSTALLATION

Yes

REPAIR or INSTALL a new damper door.

TEST the system for normal operation.

CONNECT the vacuum control motor arm to the door and check operation. TEST the system for normal operation.

Key in OFF position.
Check the attachment of the vacuum control motor arm to damper door.

Is the vacuum control motor arm attached to the door or door crank arm?

PINPOINT TEST B: INSUFFICIENT, ERRATIC, OR NO HEAT

Test Step	Result / Action to Take
B1 CHECK FOR CORRECT ENGINE COOLANT LEVEL	Yes GO to B2 . No GO to B3 .
Key in OFF position. Check the engine coolant level when hot and cold. 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	Yes GO to B4 . No TEST the engine cooling system for correct operation.
WARNING: The heater core inlet hose will become too hot to handle and may cause serious burns if the system is working correctly. Key in START position. Allow the engine to reach normal operating temperature. Feel the heater core inlet hose. Is the heater core inlet hose too hot to handle?
B3 CHECK THE ENGINE COOLING SYSTEM INCLUDING RADIATOR CAP FOR LEAKS	Yes GO to B4 . No Pressure test the heater core. REFER to Component Tests, Heater Core - Pressure Test.
Fill the engine cooling system to specified level. NOTE: It is not necessary to check the components separately at this time. Pressure check the engine cooling system. Does the engine cooling system, including the radiator cap, hold pressure?
B4 CHECK THE HEATER CORE OUTLET HOSE FOR HOT WATER	Yes TEST the heater core for a plugged or partially plugged condition. No GO to Pinpoint Test E .
Feel the heater core outlet hose. Is the heater core outlet hose cool or cold?

PINPOINT TEST C: THE A/C DOES NOT OPERATE/DOES NOT OPERATE CORRECTLY

Test Step

Result / Action to Take

C1 CHECK THE PCM PID WACF

Yes

REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.

GO to C2 .

Connect the diagnostic tool.
Turn the function selector to the OFF position.
Key in ON position.
Enter the following diagnostic mode on the diagnostic tool:
Monitor the PCM PID WACF while turning the function selector.
Does the PCM PID WACF read YES?

C2 CHECK THE PCM PID WACF WITH THE A/C ON

Yes

REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.

GO to C3 .

Turn the function selector switch to the A/C position.
Enter the following diagnostic mode on the diagnostic tool:
Monitor the PCM PID WACF while turning the function selector.
Does the PCM PID WACF read YES?

C3 CHECK THE PCM PID ACCS WITH THE A/C ON

Yes

GO to C4 .

GO to C6 .

Key in START position.
Make sure the engine is at idle.
Enter the following diagnostic mode on the diagnostic tool: PCM PID ACCS.
Monitor the PCM PID ACCS while turning the function selector.
Does the PCM PID ACCS read ON?

C4 CHECK PCM PID WAC WITH THE A/C ON

Yes

GO to C20 .

GO to C5 .

NOTE: When PCM PID WACF is YES, this is the same fault as DTC P1460.

Enter the following diagnostic mode on the diagnostic tool: PCM PID WAC.
Monitor the PCM PID WAC while turning the function selector.
Does the PCM PID WAC read ON?

C5 CHECK THE INPUT SIGNAL TO THE PCM

Yes

INSTALL a new powertrain control module. TEST the system for normal operation.

GO to C6 .

Key in OFF position.
Disconnect: PCM C175.
Key in ON position.
Measure the voltage at PCM C175-41, circuit 198 (DG/OG), harness side and ground.

Is the voltage reading greater than 10 volts?

C6 CHECK THE REFRIGERANT PRESSURE

Yes

GO to C7 .

REPAIR the leaks and RETEST the system for normal operation.

Key in OFF position.
Connect the manifold gauge set. Refer to Refrigerant System Tests in this section.
Is the system pressure 345-1,724kPa (50-250psi)?

C7 CHECK THE SUPPLY TO THE FUNCTION SELECTOR SWITCH

Yes

GO to C17 .

GO to C8 .

Key in OFF position.
Disconnect: Function Selector Switch C294c.
Key in ON position.
Measure the voltage at the function selector switch C294c-2, circuit 883 (PK/LB), harness side and ground.

Is the voltage reading greater than 10 volts?

C8 CHECK CIRCUIT 883 (PK/LB) FOR A SHORT TO GROUND

Yes

GO to C9 .

GO to C11 .

Key in OFF position.
Measure the resistance between the function selector switch C294c-2, circuit 883 (PK/ LB) harness side and ground.

Is the resistance less than 5 ohms?

C9 CHECK CIRCUIT 348 (VT) FOR SHORT TO GROUND

Yes

REPAIR circuit 348 (VT). TEST the system for normal operation.

GO to C10 .

Disconnect: A/C Cycling Switch C130.
Measure the resistance between the function selector switch C294c-4, circuit 348 (VT) harness side and ground.

Is the resistance reading less than 10,000 ohms?

C10 CHECK FOR A SHORTED FUNCTION SELECTOR SWITCH

Yes

INSTALL a new function selector switch. REFER to Section. TEST the system for normal operation.

GO to C13 .

Connect: Function Selector Switch C294c.
Measure the resistance between the A/C cycling switch C130-4, circuit 348 (VT) harness side and ground.

Turn the function selector switch to each of the following positions and note the resistance reading:

MAX A/C

A/C

VENT

FLOOR

MIX

DEFROST

Are any of the readings less than 10,000 ohms?

C11 CHECK CIRCUIT C198 (DG/OG) FOR A SHORT TO GROUND

Yes

GO to C14 .

GO to C12 .

Connect: A/C Cycling Switch C130.
Disconnect: A/C Pressure Cut-off Switch C1078.
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.
Measure the resistance between the A/C pressure cutoff switch C1078-3, circuit 198 (DG/OG), harness side and ground.

Is the resistance reading less than 10,000 ohms?

C12 CHECK THE A/C CYCLING SWITCH FOR A SHORT TO GROUND

Yes

REPAIR circuit C420 (DB/YE) for a short to ground. TEST for normal operation.

INSTALL a new A/C cycling switch. REFER to Section. TEST system for normal operation.

Disconnect: A/C Cycling Switch C130.
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.
Measure the resistance between the A/C pressure cutoff switch C1078-2, circuit 420 (DB/YE), harness side and ground.

Is the resistance reading less than 10,000 ohms?

C13 CHECK CIRCUIT 198 (DG/OG) FOR A SHORT TO GROUND

Yes

GO to C15 .

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.

Connect: A/C Pressure Cut-off Switch C1078.
Measure the resistance between PCM C175-41, circuit 198 (DG/OG), harness side and ground.

Is the resistance less than 10,000 ohms?

C14 CHECK THE A/C PRESSURE CUT-OFF SWITCH

Yes

REPAIR circuit 198 (DG/OG) for a short to ground. TEST the system for normal operation.

INSTALL a new A/C pressure cut-off switch.

Disconnect: A/C Pressure Cut-off Switch C1078.
Measure the resistance between the Rotunda EEC-V Breakout Box pin 41, circuit 198 (DG/OG), and ground.

Is the resistance less than 10,000 ohms?

C15 CHECK THE FUNCTION SELECTOR SWITCH

Yes

GO to C17 .

GO to C16 .

Key in OFF position.
Connect: Function Selector Switch C294c.
Disconnect: A/C Cycling Switch C130.
Key in ON position.
Turn the function selector switch to the A/C position.
Measure the voltage between C130-4, circuit 348 (VT), harness side and ground.

Is the voltage reading greater than 10 volts?

C16 MEASURE THE RESISTANCE OF CIRCUIT 348 (VT)

Yes

INSTALL a new function selector switch. REFER to Section. TEST the system for normal operation.

REPAIR circuit 348 (VT) for an open. TEST the system for normal operation.

Key in OFF position.
Disconnect: Function Selector Switch C294c.
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.

Is the resistance reading less than 5 ohms?

C17 MEASURE THE VOLTAGE TO THE A/C PRESSURE CUT-OFF SWITCH

Yes

GO to C19 .

GO to C18 .

Key in OFF position.
Connect: A/C Cycling Switch C130.
Disconnect: A/C Pressure Cut-off Switch C1078.
Turn the function selector switch to the A/C position.

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.
Measure the voltage at the A/C high pressure cut-off switch C1078-2 circuit 420 (DB/YE), harness side and ground.

Is the voltage reading greater than 10 volts?

C18 CHECK THE A/C CYCLING SWITCH

Yes

INSTALL a new A/C cycling switch. REFER to Section. TEST the system for normal operation.

REPAIR circuit 420 (DB/YE) for an open. TEST the system for normal operation.

Key in OFF position.
Disconnect: A/C Cycling Switch C130.
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.
Measure the resistance between A/C cycling switch C130-2, circuit 420 (DB/YE), harness side and the A/C high pressure cut-off switch C1078-2, circuit 420 (DB/YE), harness side.

Is the resistance less than 5 ohms?

C19 CHECK THE A/C PRESSURE CUT-OFF SWITCH

Yes

INSTALL a new A/C pressure cut-off switch. REFER to Section. TEST the system for normal operation.

REPAIR circuit 198 (DG/OG) for an open. TEST the system for normal operation.

Key in OFF position.
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.
Measure the resistance between Rotunda Breakout Box pin 41 and A/C high pressure cut-off switch C1078-3, circuit 198 (DG/OG), harness side.

Is the resistance less than 5 ohms?

C20 CHECK THE GROUND CIRCUIT AT THE CONSTANT CONTROL RELAY MODULE

Yes

GO to C21 .

REPAIR circuit 1205 (BK) for an open. TEST the system for normal operation.

Key in OFF position.
Disconnect: CCRM C1262.
Measure the resistance of CCRM C1262-18, circuit 1205 (BK), harness side and ground.

Is the resistance reading less than 5 ohms?

C21 CHECK CIRCUIT 20 (WH/LB) AT THE CONSTANT CONTROL RELAY MODULE

Yes

GO to C22 .

REPAIR circuit 20 (WH/LB) for an open. TEST the system for normal operation.

Key in ON position.
Measure the voltage at the CCRM C1262-13, circuit 20 (WH/LB), harness side and ground.

Is the voltage reading greater than 10 volts?

C22 CHECK THE POWER TO THE A/C CLUTCH

Yes

GO to C24 .

GO to C23 .

Key in OFF position.
Connect: CCRM 1262.
Disconnect: A/C Clutch C100.
Turn the function selector to the A/C position.

Measure the voltage at the A/C clutch C100, circuit 347 (BK/YE), harness side and ground.

Is the voltage greater than 10 volts?

C23 CHECK CIRCUIT 331 (PK/YE) FOR AN OPEN.

Yes

GO to C24 .

REPAIR circuit 331 (PK/YE) for an open. TEST the system for normal operation.

Key in OFF position.
Disconnect: CCRM C1262.
Key in ON position.
Enter the following diagnostic mode on the diagnostic tool:
In the Active Command Mode command the PCM outputs ON.
Measure the resistance between the CCRM C1262-22, circuit 331 (PK/YE), harness side and ground.

Is the resistance reading less than 5 ohms?

C24 CHECK CIRCUIT 347 (BK/YE)

Yes

GO to C25 .

REPAIR circuit 347 (BK/YE) for an open. TEST the system for normal operation.

Key in OFF position.
Measure the resistance between CCRM C1262-23, circuit 347 (BK/YE), harness side and A/C clutch C100- 1, harness side.

Is the resistance less than 5 ohms?

C25 CHECK CIRCUIT 347 (BK/YE) FOR A SHORT TO GROUND.

Yes

INSTALL a new constant control relay module. TEST the system for normal operation.

REPAIR circuit 1205 (BK) for an open. TEST the system for normal operation.

Measure the resistance between A/C clutch C100-2, circuit 1205 (BK), harness side and the CCRM C1262- 16, circuit 1205 (BK) harness side.

Is the resistance less than 5 ohms?

PINPOINT TEST D: THE A/C IS ALWAYS ON

Test Step	Result / Action to Take
D1 CHECK PCM PID WACF	Yes REPAIR circuit 331 (PK/YE) for a short to ground. TEST the system for normal operation. No GO to D2 .
Turn the function selector switch to the OFF position. Key in ON position. Enter the following diagnostic mode on the diagnostic tool: PCM PID WACF. Does the PCM PID WACF read YES?
D2 CHECK PID ACCS WITH A/C OFF	Yes GO to D3 . No GO to D5 .
Enter the following diagnostic mode on the diagnostic tool: PCM PID ACCS. Does the PCM PID ACCS read ON?	Yes GO to D3 . No GO to D5 .
D3 CHECK FOR A FALSE INPUT SIGNAL TO THE PCM	Yes GO to D4 . No INSTALL a new powertrain control module. REFER to Section. TEST the system for normal operation.
Key in OFF position. Disconnect: PCM C175. Key in ON position. Turn the function selector switch to the OFF position. Measure the voltage between PCM C175-41, circuit 198 (DG/OG) harness side and ground Is the voltage greater than 10 volts?
D4 CHECK CIRCUIT 198 (DG/OG) FOR A SHORT TO B+	Yes REPAIR circuit 348 (PK) for a short to B+. TEST the system for normal operation. No INSTALL a new function selector switch. REFER to Section. TEST the system for normal operation.
Key in OFF position. Disconnect: Function Selector Switch C294c. Connect: PCM C175. Key in ON position. Measure the voltage at the function selector switch C294c-3, circuit 348 (PK), harness side and ground. Is there voltage present?
D5 CHECK FOR A SHORTED CLUTCH INPUT	Yes INSTALL a new constant control relay module. TEST the system for normal operation. No CHECK the clutch air gap. REFER to Air Conditioning (A/C) Clutch Air Gap Adjustment .
Key in OFF position. Disconnect: A/C Clutch C100. Key in ON position. Measure for voltage at the A/C clutch C100, circuit 347 (BK/YE), harness side and ground. Is there voltage present?

PINPOINT TEST E: INSUFFICIENT A/C COOLING

Test Step

Result / Action to Take

E1 CHECK THE CENTER A/C REGISTER DISCHARGE TEMPERATURE

Yes

The tests indicate that the system is functioning normally.

GO to E2 .

Carry out the refrigerant system tests. Refer to Refrigerant System Tests in this section.
Use the recorded data from the refrigerant system tests to plot a vertical line for ambient temperature and a horizontal line for center A/C register discharge temperature.

Is the intersection of the two lines within the upper and lower limits?

E2 CHECK FOR NORMAL DISCHARGE PRESSURE

Yes

GO to E3 .

GO to E8 .

Use the recorded data from the refrigerant system tests to plot a vertical line for ambient temperature and a horizontal line for compressor discharge (high) pressure.

Is the intersection of the two lines within the upper and lower limits?

E3 EVALUATE THE SYSTEM LOW PRESSURE PERFORMANCE

Yes

GO to E4 .

GO to E6 .

Use the recorded data from the refrigerant system tests to plot a vertical line for ambient temperature and a horizontal line for compressor suction (low) pressure.

Is the intersection of the two lines within the upper and lower limits?

E4 CHECK FOR A SLOW OR CONTINUOUS RUN A/C CLUTCH CYCLE RATE

Yes

GO to E5 .

INSTALL a new A/C evaporator core due to a partially restricted or plugged condition. REFER to Section. TEST the system for normal operation.

Use the recorded data from the refrigerant system tests to plot a vertical line for ambient temperature and a horizontal line for total A/C clutch cycle time (time ON plus time OFF) in seconds.

Is the intersection of the two lines above the upper limit?

E5 CHECK FOR A LONG OR CONTINUOUS A/C CLUTCH OFF TIME

Yes

DISCHARGE and RECOVER the system to remove excessive moisture or refrigerant oil. REFER to Air Conditioning (A/C) System Recovery, Evacuation and Charging . TEST the system for normal operation.

GO to E7 .

Use the recorded data from the refrigerant system tests to plot a vertical line for ambient temperature and a horizontal line for A/C clutch OFF time in seconds.

Is the intersection of the two lines above the upper limit?

E6 CHECK FOR A HIGH SUCTION PRESSURE

Yes

REMOVE the A/C evaporator core orifice to repair missing or damaged (leaking) O-ring seals. REFER to Section. TEST the system for normal operation.

INSTALL a new A/C cycling switch when the intersection of the two lines is below the lower limit. REFER to Section. TEST the system for normal operation.

Refer to the data plot used to evaluate the system low pressure performance in Step E3.
Is the intersection of the two lines above the upper limit?

E7 CHECK THE AMBIENT TEMPERATURE

Yes

This is normal operation for the refrigerant system in high humidity conditions.

DISCHARGE and RECOVER the system to correct an overcharge condition. REFER to Air Conditioning (A/C) System Recovery, Evacuation and Charging . TEST the system for normal operation.

Refer to the data plot used to evaluate the system A/C clutch OFF time in Step E5.
Is the ambient temperature above 26C (80F)?

E8 CHECK FOR A HIGH DISCHARGE PRESSURE

Yes

GO to E9 .

GO to E11 .

Refer to the data plot used to evaluate the system high pressure performance in Step E2.
Is the intersection of the two lines above the upper limit?

E9 CHECK FOR A NORMAL LOW PRESSURE

Yes

REFER to Section to diagnose the engine cooling system.

TEST the system for normal operation.

GO to E10 .

Use the recorded data from the refrigerant system tests to plot a vertical line for ambient temperature and a horizontal line for compressor suction (low) pressure.

Is the intersection of the two lines within the upper and lower limits?

E10 CHECK FOR A NORMAL TO LOW SUCTION PRESSURE

Yes

INSTALL a new A/C evaporator core orifice due to a partially restricted or plugged condition. REFER to Section. TEST the system for normal operation.

INSPECT the A/C condenser core (19712) for a partially blocked or inadequate airflow.

TEST the system for normal operation.

Refer to the data plot used to evaluate the system low pressure performance in Step E9.
Is the intersection of the two lines below the lower limit?

E11 CHECK FOR A NORMAL SUCTION PRESSURE

Yes

GO to E12 .

GO to E15 .

Use the recorded data from the refrigerant system tests to plot a vertical line for ambient temperature and a horizontal line for compressor suction (low) pressure.

Is the intersection of the two lines within the upper and lower limits?

E12 CHECK FOR A SLOW A/C CLUTCH CYCLE RATE

Yes

INSTALL a new evaporator to compressor suction line (19D742) due to a partially restricted or plugged condition.

REFER to Section.

TEST the system for normal operation.

GO to E13 .

Use the recorded data from the refrigerant system tests to plot a vertical line for ambient temperature and a horizontal line for total A/C clutch cycle time (time ON plus time OFF) in seconds.

Is the intersection of the two lines above the upper limit?

E13 CHECK FOR A NORMAL A/C CLUTCH OFF TIME

Yes

INSPECT the A/C evaporator core due to a low or restricted airflow. TEST the system for normal operation.

GO to E14 .

Use the recorded data from the refrigerant system tests to plot a vertical line for ambient temperature and a horizontal line for A/C clutch OFF time in seconds

Is the intersection of the two lines within the upper and lower limits?

E14 CHECK FOR A LONG A/C CLUTCH OFF TIME

Yes

INSTALL a new A/C condenser core due to a partially restricted or plugged condition. REFER to Section. TEST the system for normal operation.

EVACUATE and RECHARGE the system when the intersection of the two lines is below the lower limit. REFER to Air Conditioning (A/C) System Recovery, Evacuation and Charging . TEST the system for normal operation.

Refer to the data plot used to evaluate the system A/C clutch OFF time performance in Step E13.
Is the intersection of the two lines above the upper limit?

E15 CHECK FOR A MISSING A/C EVAPORATOR CORE ORIFICE

Yes

INSTALL a new A/C evaporator core orifice.

REFER to Section.

TEST the system for normal operation.

INSTALL a new A/C compressor due to low performance. REFER to Section. TEST the system for normal operation.

Remove the A/C evaporator core orifice tube. Refer to Section.
Is the A/C evaporator core orifice missing?

PINPOINT TEST F: NO OPERATION IN ALL TEMPERATURE SETTINGS

Test Step	Result / Action to Take
F1 CHECK THE TEMPERATURE CONTROL	Yes The temperature blend door is functioning correctly. RETURN to the symptom chart. No GO to F2 .
Start the engine and run at idle. Allow the engine to reach normal operating temperature. Place the function selector switch in the NORMAL A/C position. Adjust the temperature control to full warm position, and physically feel the discharge air temperature at the at the center panel vents. Rotate the temperature control to full cold position, and physically feel the discharge air temperature at the center panel vents. Does the discharge air temperature vary?
F2 CHECK FOR A BROKEN A/C TEMPERATURE CONTROL CABLE	Yes INSTALL a new evaporator housing. REFER to Section. No INSTALL a new temperature control cable assembly.
Remove the climate control assembly to gain access to the control cable head. Move the temperature control from full warm to full cold. Inspect the cable control head as you move the temperature control. Does the alignment mark on the control head move?

PINPOINT TEST G: THE BLOWER MOTOR DOES NOT OPERATE/DOES NOT OPERATE CORRECTLY

Test Step

Result / Action to Take

G1 CHECK FOR VOLTAGE AT C238

Yes

GO to G2 .

GO to G4 .

Disconnect: Blower Motor Jumper C238.
Key in ON position.
Turn the blower motor selector to LOW.
Turn the function selector to FLOOR.
Check for voltage between C238-6, circuit 249 (DB/LG) and C238-3, circuit 261 (OG/BK).

Is the voltage greater than 10 volts?

G2 CHECK THE BLOWER MOTOR FOR VOLTAGE

Yes

INSTALL a new blower motor. REFER to Section. TEST the system for normal operation.

GO to G3 .

Key in OFF position.
Connect: Blower Motor Jumper C238.
Disconnect: Blower Motor C2066.
Key in ON position.
Measure voltage between terminals of blower motor.

Check for voltage between circuit 249 (DB/LG) and circuit 261 (OG/BK).
Is the voltage greater than 10 volts?

G3 CHECK THE A/C BLOWER MOTOR JUMPER WIRE

Yes

REPAIR circuit 261 (OG/BK). TEST the system for normal operation.

INSTALL a new blower motor. REFER to Section. TEST the system for normal operation.

Key in OFF position.
Disconnect: Blower Motor Jumper C238.
Key in ON position.
Check circuit 261 (OG/BK) for an open between C2066 and C238-4.

Is the resistance greater than 5 ohms?

G4 CHECK CIRCUIT 249 (DB/LG)

Yes

GO to G5 .

GO to G8 .

Check for voltage between C238-6, circuit 249 (DB/LG), harness side and ground.

Is the voltage greater than 10 volts?

G5 CHECK CIRCUIT 249 (DB/LG) FOR OPEN

Yes

REPAIR circuit 249 (DB/LG) for an open. TEST the system for normal operation.

GO to G6 .

Check the resistance on circuit 249 (DB/LG) between C238- 3 and C2066

Is resistance less than 10,000 ohms?

G6 CHECK THE BLOWER MOTOR GROUND

Yes

GO to G7 .

GO to G10 .

Key in OFF position.
Measure the resistance between the jumper C238-3, circuit 261 (OG/BK), and ground.

Is the resistance less than 5 ohms?

G7 CHECK CIRCUIT 261 (OG/BK) FOR AN OPEN CIRCUIT

Yes

REPAIR the blower motor jumper. TEST the system for normal operation.

INSTALL a new blower motor. REFER to Section. TEST the system for normal operation.

Measure the resistance between the A/C blower motor jumper C238-3, circuit 261 (OG/BK) and the blower motor switch C294a-1.

Is the resistance more than 10,000 ohms?

G8 CHECK CIRCUIT 249 (DB/LG) FOR AN OPEN CIRCUIT

Yes

REPAIR circuit 249 (DB/LG) for an open. TEST the system for normal operation.

GO to G9 .

Key in OFF position.
Disconnect: Function Selector Switch C294c.
Measure the resistance between C238-3, circuit 249 (DB/LG), harness side and C294c-4 harness side.

Is the resistance more than 10,000 ohms?

G9 CHECK CIRCUIT 181 (BN/OG), FOR VOLTAGE

Yes

INSTALL a new function selector switch. REFER to Section. TEST the system for normal operation.

REPAIR circuit 181 (BN/OG) for an open. TEST the system for normal operation.

Measure the voltage between C294c-2, circuit 181 (BN/OG), harness side and ground.

Is the voltage greater than 10 volts?

G10 CHECK CIRCUIT 1205 (BK) FOR AN OPEN

Yes

INSTALL a new blower motor switch. REFER to Section. TEST the system for normal operation.

REPAIR circuit 1205 (BK).

TEST the system for normal operation.

Check the resistance between C294a-3, circuit 1205 (B/K) harness side and ground.
Is the resistance less than 5 ohms?

PINPOINT TEST H: THE BLOWER MOTOR OPERATES CONTINUOUSLY IN HIGH SPEED

Test Step	Result / Action to Take
H1 CHECK THE FUNCTION SELECTOR SWITCH	Yes GO to H2 . No If the blower motor operates in the OFF position, GO to H4
Key in ON position. Set the blower motor speed to low. Check for blower motor operation in each function selector switch position. Does the blower motor operate on high in all of the function selector positions?
H2 CHECK CIRCUIT 261 (OG/BK) FOR A SHORT TO GROUND	Yes GO to H3 . No REPAIR circuit 261 (OG/BK) for a short to ground. TEST the system for normal operation.
Key in OFF position. Disconnect: A/C Blower Motor C2066. Disconnect: Blower Motor Resistor C2185. Disconnect: Blower Motor Switch C294a. Measure the resistance between C2066 circuit 261 (OG/BK), and ground. Is the resistance greater than 10,000 ohms?
H3 CHECK THE BLOWER MOTOR SWITCH OPERATION	Yes INSTALL a new heater blower motor switch resistor. REFER to Section. TEST the system for normal operation. No INSTALL a new heater blower motor switch. REFER to Section. TEST the system for normal operation
Measure the resistance of the blower motor switch. Refer to the chart shown. Blower Motor Switch Test Is the resistance less than 5 ohms?
H4 CHECK THE FUNCTION SELECT SWITCH FOR A SHORT TO BATTERY	Yes INSTALL a new function selector switch. REFER to Section. TEST the system for normal operation. No REPAIR circuit 249 (DB/LG) for a short to battery. TEST the system for normal operation.
Key in OFF position. Disconnect: Function Selector Switch C294c. Key in ON position. Did the blower motor stop operating?

PINPOINT TEST I: NO OPERATION IN HIGH BLOWER SETTING

Test Step	Result / Action to Take
I1 CHECK CIRCUIT 261 (OG/BK) FOR AN OPEN CIRCUIT	Yes GO to I2 . No REPAIR circuit 261 (OG/BK) for an open circuit. TEST the system for normal operation.
Key in OFF position. Disconnect: Blower Motor Switch C294a. Key in ON position. Turn the function selector switch to the FLOOR position. Measure the voltage between blower motor switch C294a, circuit 261 (OG/BK), harness side and ground. Is the voltage greater than 10 volts?
I2 CHECK CIRCUIT 1205 (BK) FOR AN OPEN	Yes REPAIR circuit 1205 (BK) for an open. TEST the system for normal operation. No INSTALL a new blower motor switch. REFER to Section. TEST the system for normal operation.
Measure the resistance between C294a-3, circuit 1205 (BK), harness side and ground. Is the resistance less than 10,000 ohms?

PINPOINT TEST J: NO OPERATION IN LOWER SPEEDS

Test Step	Result / Action to Take
J1 CHECK CIRCUIT 261 (OG/BK) FOR AN OPEN	Yes GO to J2 . No REPAIR circuit 261 (OG/BK) for an open circuit between the blower motor and the blower motor resistor. TEST the system for normal operation.
Disconnect: Blower Motor Resistor C294a. Key in ON position. Turn the function selector switch to the FLOOR position. Set the blower motor switch to low. Measure the voltage between the blower motor resistor C2185-4, circuit 261 (OG/BK), jumper side and ground. Is the voltage greater than 10 volts?
J2 CHECK CIRCUIT 1205 (BK) FOR AN OPEN	Yes INSTALL a new blower motor resistor. REFER to Section. TEST the system for normal operation. No REPAIR circuit 1205 (BK) for an open between the blower motor resistor and ground. TEST the system for normal operation.
Key in OFF position. Measure the resistance between the blower motor resistor C2185-1, circuit 1205 (BK), jumper side and ground. Is the resistance less than 5 ohms?

Symptom Chart

Condition Possible Sources Action Incorrect/erratic direction of airflow from outlet(s) No vacuum to A/C heater function switch selector. A/C heater funct ...

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