Test Procedure

WARNING: This page is about a different car, the 2009 Ford RV Cutaway, 2009 Ford Econoline, 2009 Ford E450 Super Duty, and 2009 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

AV1 PRELIMINARY DIAGNOSIS DIAGNOSTIC TROUBLE CODE (DTC) P0645

Carry out a visual inspection.
Retrieve and record all DTCs.
Clear all DTCs.
Carry out the on-demand self-test.

Is DTC P0645 present?

Yes	No
GO to AV2.	Unable to duplicate the condition. CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the concern. REPAIR as necessary. REFER to the appropriate, Climate Control System and diagnose the air conditioning (A/C) is inoperative/does not operate correctly symptom.

AV2 DTC P0645

Possible causes:
- A/C clutch relay control circuit short to voltage
- A/C clutch relay control circuit open
- A/C clutch relay control circuit short to ground
- A/C clutch relay circuit
- A/C clutch relay
- PCM
Ignition ON, engine OFF.
Access the PCM and monitor the ACCS PID.
Cycle the A/C control switch off and on.

Does the ACCS PID indicate ON with the A/C control switch ON and OFF with the A/C control switch OFF?

Yes	No
GO to AV3.	REFER to the appropriate, Climate Control System and diagnose the air conditioning (A/C) is inoperative/does not operate correctly symptom.

AV3 CHECK THE A/C CLUTCH RELAY COIL POWER CIRCUIT FOR VOLTAGE

NOTE: Refer to the appropriate Wiring Diagrams article for the A/C clutch relay coil pin locations.

Ignition OFF.
A/CC Relay connector disconnected.
Ignition ON, engine OFF.
Measure the voltage between:

(+) A/CC Relay Connector, Harness Side	(-)
VPWR - Pin 1	Ground

Is the voltage greater than 10 V?

Yes	No
GO to AV4.	REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

AV4 CHECK THE A/C CLUTCH RELAY CONTROL CIRCUIT

Connect a non-powered test lamp between:

Point A A/CC Relay Connector, Harness Side	Point B A/CC Relay Connector, Harness Side
VPWR - Pin 1	A/CCR - Pin 2

Ignition ON, engine running.
Cycle the A/C control switch off and on.

Is the test lamp illuminated with the A/C control switch on and is the test lamp off with the A/C control switch off?

Yes	No
REFER to the appropriate, Climate Control System and diagnose the air conditioning (A/C) is inoperative/does not operate correctly symptom.	GO to AV5.

AV5 CHECK THE A/C CLUTCH RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE

Ignition OFF.
PCM connector disconnected.
Ignition ON, engine OFF.
Measure the voltage between:

(+) PCM Connector, Harness Side	(-)
A/CCR - Pin B2	Ground

Is the voltage less than 0.2 V?

Yes	No
GO to AV6.	REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

AV6 CHECK THE A/C CLUTCH RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND

Ignition OFF.
Measure the resistance between:

(+) PCM Connector, Harness Side	(-)
A/CCR - Pin B2	Ground

Is the resistance greater than 10K ohms?

Yes	No
GO to AV7.	REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

AV7 CHECK THE A/C CLUTCH RELAY CONTROL CIRCUIT FOR AN OPEN

Measure the resistance between:

(+) PCM Connector, Harness Side	(-) A/CC Relay Connector, Harness Side
A/CCR - Pin B2	A/CCR - Pin 2

Is the resistance less than 5 ohms?

Yes	No
GO to AV8.	REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

AV8 CHECK FOR CORRECT PCM OPERATION

Disconnect all the PCM connectors.
Visually inspect for:
- pushed out pins
- corrosion
Connect all the PCM connectors and make sure they seat correctly.
Carry out the PCM self-test and verify the concern is still present.

Is the concern still present?

Yes	No
INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) , Programming the VID Block for a Replacement PCM.	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.