Pinpoint Test O : The Air Conditioning (A/C) Is Inoperative

WARNING: This page is about a different car, the 2017 Lincoln Navigator and 2017 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

O1 CHECK THE A/C SYSTEM PRESSURE

Ignition OFF.

With the manifold gauge set connected, check the A/C system pressure.

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

Yes	GO to O2.
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.

O2 CHECK THE COMMUNICATION NETWORK

Ignition ON.

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

Do the BCM and the PCM pass the network test?

Yes	GO to O3.
No	DIAGNOSE the BCM or PCM does not communicate with the diagnostic scan tool. REFER to: Module Communications Network .

O3 CHECK THE PCM (A/C) PRESSURE SENSOR (ACP_PRESS) PID
- Using a diagnostic scan tool, monitor the ACP_PRESS PCM PID.
- With the 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 O4.

No GO to Pinpoint Test A .

O4 COMPARE THE PCM INTAKE AIR TEMPERATURE (IAT) PID AND THE OTHER TEMPERATURE SENSOR READINGS TO THE PCM AMBIENT AIR TEMPERATURE (AAT) PID

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 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 O5.
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) .

O5 CHECK THE HVAC EVAPORATOR TEMPERATURE (EVAP_TEMP) PID

Using a diagnostic scan tool, view HVAC control module PIDs.

Monitor the EVAP_TEMP PID.

Does the evaporator temperature sensor PID read similar (typically within 18 °C (32.4 °F) to the ambient temperature?

Yes	GO to O6.
No	DIAGNOSE the evaporator temperature sensor. GO to Pinpoint Test G .

O6 CHECK THE FCIM (A/C) SWITCH (CC_SW_AC) PID WITH THE A/C ON
- Start the engine.
- Using a diagnostic scan tool, monitor the FCIM CC_SW_AC PID.
- Select PANEL and press the A/C button (indicator on) on the HVAC controls.
Does the PID display Active when the button is pressed and the indicator is on?

Yes GO to O7.

No GO to O16.

O7 CHECK THE PCM AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PID WITH THE A/C ON
- Using a diagnostic scan tool, monitor the PCM AC_REQ PID.
- Select PANEL and press the A/C button (indicator on) on the HVAC controls.
Does the AC_REQ PID read YES when the button is pressed and the indicator is on?

Yes GO to O9.

No GO to O8.

O8 RESET THE AMBIENT AIR TEMPERATURE (AAT) SENSOR

On the HVAC controls, press the A/C and Recirc buttons simultaneously, then release both. Within 2 seconds press A/C button again.

Start the engine.

On the HVAC controls, set the temperature to full cold, select PANEL and select the A/C button (indicator on).

Does the A/C compressor turn on?

Yes	RETEST the A/C system for normal operation. CARRY OUT the refrigerant system tests. Refer to the appropriate Refrigerant System Tests procedure in this article.
No	GO to O9.

O9 CHECK THE PCM AIR CONDITIONING COMPRESSOR COMMANDED STATE (ACC_CMD) PID WITH THE A/C COMMANDED ON
- Using a diagnostic scan tool, activate the PCM ACC_CMD PID.
Does the A/C compressor turn on?

Yes GO to O17.

No GO to O10.

O10 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 1	Courtesy of FORD MOTOR COMPANY	Ground
Courtesy of FORD MOTOR COMPANY A/C clutch relay socket 3	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes	GO to O11.
No	VERIFY Battery Junction Box (BJB) fuses 79 (15A) and 30 (10A) are OK. If OK, REPAIR the circuit in question. TEST the system for normal operation. If not OK, REFER to the OEM Electrical Wiring Diagram Introduction to identify the possible causes of the circuit short.

O11 CHECK THE A/C CLUTCH RELAY CONTROL GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: PCM C175B.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Courtesy of FORD MOTOR COMPANY A/C clutch relay socket 2	Courtesy of FORD MOTOR COMPANY	C175B-2

Is the resistance less than 3 ohms?

Yes	GO to O12.
No	REPAIR the circuit.

O12 BYPASS THE A/CA/C CLUTCH RELAY

Ignition OFF.

Connect a fused jumper wire:

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

Start the engine.

Does the A/C compressor clutch engage?

Yes	REMOVE the fused jumper wire. INSTALL a new A/C clutch relay.
No	LEAVE the fused jumper wire installed. GO to O13.

O13 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: A/C compressor clutch field coil C100.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C100-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes	REMOVE the fused jumper wire. GO to O14.
No	REMOVE the fused jumper wire. REPAIR the circuit.

O14 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 O15.
No	REPAIR the circuit.

O15 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 average greater than 0.65 mm (0.026 in)?

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

O16 CHECK FOR CORRECT HVAC CONTROL MODULE OPERATION

Disconnect and inspect all HVAC control 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 all HVAC control module connectors. Make sure they seat and latch correctly.

Operate the system and verify 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 control module. REFER to Climate Control .
No	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.

O17 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 table below. Refer to the reference value information in 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 Failsafe 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 O7.
No	GO to O16.

Yes	GO to O17.
No	GO to O10.