Pinpoint Test L : The A/C Is Inoperative

WARNING: This page is about a different car, the 2016 Lincoln MKS. However, it is still accessible from the selected car via links, so may be relevant.

L1 CHECK THE A/C SYSTEM PRESSURE

Ignition OFF.

With the R-134a manifold gauge set connected, check the A/C system pressure.

Is the A/C system pressure above 290 kPa (42 psi) ?

Yes	GO to L2.
No	CHECK the A/C system for leaks. REFER to Fluorescent Dye Leak Detection or Electronic Leak Detection . RECHARGE the A/C system. REFER to Air Conditioning (A/C) System Recovery, Evacuation and Charging . TEST the system for normal operation.

L2 CHECK THE COMMUNICATION NETWORK

Ignition ON.

Using a diagnostic scan tool, carry out the network test.

Do the FCIM, HVAC module and the PCM pass the network test?

Yes	GO to L3.
No	DIAGNOSE the FCIM, HVAC module or PCM does not communicate with the diagnostic scan tool. REFER to: Module Communications Network .

L3 CHECK THE PCM (POWERTRAIN CONTROL MODULE) A/C (AIR CONDITIONING) PRESSURE SENSOR (ACP_PRESS) PID (PARAMETER IDENTIFICATION)
- Using a diagnostic scan tool, monitor the ACP_PRESS PCM PID.
- With the R-134a manifold gauge set connected, compare the pressure readings of the manifold gauge set and the ACP_PRESS PID.
Are the pressure values of the manifold gauge set and the ACP_PRESS PID within ± 15 psi (103 kPa)?

Yes GO to L4.

No GO to Pinpoint Test A .

L4 ELECTRIC COOLING FAN FUNCTIONAL CHECK

Using a diagnostic scan tool, carry out the PCM KOEO self-test.

Does the electric cooling fan operate sometime during the KOEO self-test?

Yes	GO to L5.
No	DIAGNOSE the electric cooling fan operation. REFER to ENGINE CONTROLS - SYMPTOM CHARTS (EXCEPT DIESEL & HYBRID) .

L5 COMPARE THE PCM (POWERTRAIN CONTROL MODULE) INTAKE AIR TEMPERATURE (IAT) PID (PARAMETER IDENTIFICATION) AND THE OTHER TEMPERATURE SENSOR READINGS TO THE PCM (POWERTRAIN CONTROL MODULE) AMBIENT AIR TEMPERATURE (AAT) PID (PARAMETER IDENTIFICATION)

NOTE: Compare multiple engine sensor readings to the ambient temperature to determine sensors are reading correctly. A faulty sensor can cause the PCM to disable the A/C with or without a DTC.

Allow the vehicle exterior and interior to stabilize to ambient temperature. This can take a soak period of at least 6 hours.

Using a diagnostic scan tool, view PCM Parameter Identifications (PIDs).

Monitor the AAT, CACT, CHT, ECT, IAT, IAT2, MAF, MAPT, TCB and TCIPT PIDs (as applicable).

Are the temperature values similar (typically within 18°C (32.4°F)?

Yes	GO to L6.
No	DIAGNOSE the suspect temperature sensor. REFER to Information Center - Instrumentation, Message Center, And Warning Chimes for Ambient Air Temperature (AAT) sensor or Outside Air Temperature Display concerns. For all other temperature sensor concerns, REFER to ENGINE CONTROLS - INTRODUCTION (EXCEPT DIESEL & HYBRID) .

L6 CHECK THE A/C EVAPORATOR TEMPERATURE (EVAP_TEMP) PID (PARAMETER IDENTIFICATION)

Using a diagnostic scan tool, view HVAC module Parameter Identifications (PIDs).

Monitor the EVAP_TEMP HVAC module PID (PARAMETER IDENTIFICATION)

Does the PID (PARAMETER IDENTIFICATION) read similar to the ambient temperature?

Yes	If equipped with the active grille shutter system, GO to L7. If not equipped with the active grille shutter system, GO to L8.
No	INSTALL a new evaporator temperature sensor (part of 19850). REFER to Climate Control , Heater Core And Evaporator Core Housing procedure.

L7 VERIFY THE GRILLE SHUTTER OPERATION USING THE PCM (POWERTRAIN CONTROL MODULE) GRILL SHUTTER A POSITION - COMMANDED (GRILL_A_CMD) PID (PARAMETER IDENTIFICATION)

Start the engine and allow it to idle for at least 30 seconds to allow for the grille shutter calibration to complete.

Using a diagnostic scan tool, view PCM PID (PARAMETER IDENTIFICATION).

Using a diagnostic scan tool, select the PCM PID (PARAMETER IDENTIFICATION) GRILL_A_CMD and command the grille shutter from 100% (open) to 0% (closed) while observing the grille shutter operation from the front of the vehicle.

Does the grille shutter fully open and close when commanded by the scan tool?

Yes	GO to L8.
No	DIAGNOSE the active grille shutter is inoperative or does not operate correctly. REFER to Front End Body Panels .

L8 CHECK THE (A/C) SWITCH (CC_SW_AC) FCIM PID WITH THE A/C ON

Using a diagnostic scan tool, view FCIM PID (PARAMETER IDENTIFICATION).

Monitor the CC_SW_AC FCIM PID (PARAMETER IDENTIFICATION)

Select PANEL, press the A/C button (indicator on) on the HVAC controls.

Does the PID (PARAMETER IDENTIFICATION) read Active when the button is pressed?

Yes	GO to L9.
No	For 8 Inch (203mm) Touch Screen, 10 Speakers, REFER to Information and Entertainment Systems - 8-Inch (203 mm) Touchscreen, 10 Speakers Symptom Chart. For THX, 8 Inch (203mm) Touch Screen, 14 Speakers, REFER to Information and Entertainment Systems - THX® 8-Inch (203 mm) Touchscreen, 16 Speakers Symptom Chart.

L9 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH THE A/C ON
- Using a diagnostic scan tool, view PCM PID (PARAMETER IDENTIFICATION).
- Select PANEL, press the A/C button (indicator on) on the HVAC controls.
- Monitor the AC_REQ PCM PID
Does the PID (PARAMETER IDENTIFICATION) read ON when the button is pressed?

Yes GO to L10.

No GO to L16.

L10 CHECK THE AIR CONDITIONING COMPRESSOR COMMANDED STATE (ACC_CMD) PID (PARAMETER IDENTIFICATION) WITH THE A/C COMMANDED ON
- Start the engine.
- Enter the following diagnostic mode on the scan tool: DataLogger - PCM.
- Command the A/C compressor on using the ACC_CMD PID.
Does the A/C compressor turn on?

Yes GO to L17.

No GO to L11.

L11 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY

Ignition OFF.

Disconnect: A/C Clutch Relay.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Courtesy of FORD MOTOR COMPANY A/C clutch relay socket 3 (component side)	Courtesy of FORD MOTOR COMPANY	Ground
Courtesy of FORD MOTOR COMPANY A/C clutch relay socket 2 (component side)	Courtesy of FORD MOTOR COMPANY	Ground

Are the voltages greater than 11 volts?

Yes	GO to L12.
No	VERIFY BJB fuses 62 (10A) and 70 (15A) are OK. If OK, REPAIR the circuit. If not OK, REFER to the OEM Electrical Wiring Diagram Introduction to identify the possible causes of the circuit short.

L12 BYPASS THE A/C CLUTCH RELAY

Measure:

Positive Lead	Measurement / Action	Negative Lead
Courtesy of FORD MOTOR COMPANY A/C clutch relay socket 3 (component side)	Courtesy of FORD MOTOR COMPANY	Courtesy of FORD MOTOR COMPANY A/C clutch relay socket 5 (component side)

Does the A/C compressor clutch engage?

Yes	REMOVE the jumper wire. INSTALL a new A/C clutch relay.
No	LEAVE the jumper wire installed. GO to L13.

L13 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: A/C Compressor Clutch Field Coil.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C100	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes	REMOVE the jumper wire. GO to L14.
No	REMOVE the jumper wire. REPAIR the circuit.

L14 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C100-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes	GO to L15.
No	REPAIR the circuit.

L15 CHECK THE A/C COMPRESSOR CLUTCH AIR GAP

Measure the A/C compressor clutch air gap at 3 equally spaced locations between the clutch hub and the A/C compressor clutch pulley.

Courtesy of FORD MOTOR COMPANY

Is the A/C compressor clutch air gap greater than 0.6 mm (0.0236 in)?

Yes	ADJUST the A/C compressor clutch gap. REFER to Air Conditioning (A/C) Clutch Air Gap Adjustment .
No	INSTALL a new clutch and clutch field coil. REFER to Clutch and Clutch Field Coil . TEST the system for normal operation.

L16 CHECK FOR CORRECT HVAC MODULE OPERATION

Ignition OFF.

Disconnect and inspect all HVAC module connectors.

Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary

Reconnect the HVAC control module connectors. Make sure they seat and latch correctly.

Operate the system and determine if the concern is still present.

Is the concern still present?

Yes	CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no TSB addresses this concern, INSTALL a new HVAC module. REFER to Climate Control .
No	The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.

L17 CHECK FOR AN INPUT DISABLING THE A/C CLUTCH RELAY

NOTE: The PCM strategy may disable the A/C compressor operation. If the A/C compressor clutch can be commanded on using IDS PCM Parameter Identifications (PIDs) Active Commands, PCM replacement will not resolve the condition.

Diagnose the PCM not energizing the A/C clutch relay using the suggestions in the chart below. Refer to the ENGINE CONTROLS - REFERENCE VALUES (EXCEPT DIESEL & HYBRID) .

A/C Clutch Engagement is inhibited because strategy has not yet detected hardware that indicates vehicle is equipped with A/C
A/C Clutch Engagement is inhibited because the strategy is operating in Ignition System Failure Mode
A/C Clutch Engagement is inhibited because the (ECU) received a Request to Command the A/C Off
A/C Clutch Engagement is inhibited because the engine has not yet reached a stable running mode after starting
A/C Clutch Engagement is inhibited because the A/C Discharge (Head) Pressure is Too High
A/C Clutch Engagement is inhibited because the Engine Coolant Temperature is Too High
A/C Clutch Engagement is inhibited to Prevent Frost and Ice Build Up on the Evaporator
A/C Clutch Engagement is inhibited to Prevent an Engine Stall during a Low Engine Speed condition
A/C Clutch Engagement is inhibited to Protect the Compressor from a Compressor Over-speed condition
A/C Clutch Engagement is inhibited to temporarily make more power available when Accelerator Pedal is Fully Depressed
A/C Clutch Engagement is inhibited because Low A/C Refrigerant Charge has been detected
A/C Clutch Engagement is inhibited to Protect the Compressor from Operating at Too Low of an Ambient Temperature
A/C Clutch Engagement is inhibited due to Missing Climate Control Message
A/C Clutch Engagement is inhibited because the strategy is operating in Fail-safe Cooling Mode
A/C Clutch Engagement is inhibited to Protect the Clutch from Damage because the Compressor Load and Speed are Too High
A/C Clutch Engagement is inhibited by the off portion of the A/C Cycling Strategy invoked to manage High Engine Temperature
A/C Clutch Engagement is inhibited due to Low Battery State of Charge
A/C Clutch Engagement is inhibited to Protect the Variable Displacement Compressor from Operating at Too Low of a Temperature
A/C Clutch Engagement is inhibited to improve Brake Booster Vacuum
A/C Clutch Engagement is inhibited because Evaporator Temperature is sufficiently low and compressor was at minimum displacement
A/C Clutch Engagement is inhibited (Disabled) because the Evaporator Temperature is sufficiently below the target temperature
A/C Clutch Engagement is inhibited to satisfy A/C Clutch minimum off time
A/C Clutch Engagement is inhibited Due to Request from Torque Control Strategy (to Temporarily Make More Power Available)
A/C Clutch Engagement is inhibited to Prevent Engine Stalling
A/C Clutch Engagement is inhibited Due to Request to Disable A/C from Stop-Start Strategy
A/C Clutch Engagement is inhibited (Delayed) to make Power Available for Power Steering
A/C Clutch Engagement Is Inhibited Due To State Of Auxiliary A/C Disable (Typically A Pressure Or Temperature) Switch 1 input
A/C Clutch Engagement is inhibited due to state of auxiliary A/C Disable (Typically a Pressure or Temperature) Switch 2 input

Are any of the conditions described above not within normal parameters?

Yes

DIAGNOSE the condition found to be disabling the A/C clutch relay. REFER to the appropriate Service Information article or the ENGINE CONTROLS - INTRODUCTION (EXCEPT DIESEL & HYBRID) .

The A/C compressor clutch can be commanded on using the IDS PCM Active command PID. The A/C inoperative concern may be caused by an intermittent condition due to a component or module connection, wiring or pin issue. ADDRESS the root cause of any connector or pin issues. CHECK the vehicle service history for recent service actions that have replaced modules. This condition may be due to incomplete or incorrect PMI (programmable module installation) procedures.

Yes	GO to L10.
No	GO to L16.

Yes	GO to L17.
No	GO to L11.