DS: Air Conditioning Pressure (ACP) Sensor

DS: Introduction See: DS: Air Conditioning Pressure (ACP) Sensor - Introduction

DS1 DTC P1461: CHECK ACP V PID

• Connect scan tool.
• Key on, engine off.
• Access ACP V PID.

Is ACP V PID less than 4.9 volts?
Yes

• The ACP circuit voltage is now below the maximum. GO to DS18

to determine if an intermittent condition exists.

No

• KEY OFF. A hard fault is present. GO to DS2

.

DS2 CHECK VOLTAGE BETWEEN VREF AND SIG RTN CIRCUITS TO ACP SENSOR

• Disconnect ACP sensor.
• Key on, engine off.
• Measure voltage between VREF and SIG RTN circuits at the ACP sensor harness connector.

Is voltage between 4.0 and 6.0 volts?
Yes

• GO to DS3

.

No

• VREF is out of range, or SIG RTN circuit to ACP sensor is open. KEY OFF. GO to C1 See: C: Reference Voltage - Pinpoint Test

.

DS3 INDUCE OPPOSITE ACP SIGNAL

• Key on, engine off.
• Again access ACP V PID.

Is ACP V PID now less than 4.9 volts?
Yes

• KEY OFF. REPLACE ACP sensor. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

No

• KEY OFF. GO to DS4.

DS4 CHECK ACP CIRCUIT FOR SHORT TO VREF IN HARNESS

• Disconnect scan tool from DLC.
• Disconnect PCM.
• Measure resistance between ACP and VREF circuits at the ACP sensor harness connector.

Is resistance greater than 10,000 ohms?
Yes

• GO to DS5

.

No

• REPAIR short circuit. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

DS5 CHECK ACP CIRCUIT FOR SHORT TO POWER IN HARNESS

• Key on, engine off.
• Measure voltage between ACP circuit at the ACP sensor vehicle harness connector and chassis ground.

Is voltage less than 1.0 volt?
Yes

• For Escort, LS6/LS8:
• KEY OFF. GO to DS6

.

• All others:
• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM). START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

No

• REPAIR short circuit. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

DS6 CHECK FOR OPEN ACP CIRCUIT IN HARNESS

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

• Measure resistance of ACP circuit between PCM harness connector pin and the ACP sensor harness connector.

Is resistance less than 5.0 ohms?
Yes

• GO to DS7

.

No

• REPAIR open circuit. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

DS7 CHECK PCM

• Reconnect PCM.
• Connect a jumper wire between the ACP and SIG RTN Circuits at the ACP sensor harness connector.
• Key on, engine off.
• Access ACP V PID.

Note: If the scan tool is now unable to communicate, follow NO Action to Take.
Is ACP V PID now less than 4.9 volts?
Yes

• REPLACE ACP sensor. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

No

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM). START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

DS10 DTC P1462: CHECK ACP V PID

• Connect scan tool.
• Key on, engine off.
• Access ACP V PID.

Is ACP V PID greater than 0.15 volt?
Yes

• The ACP circuit voltage is now above the minimum. GO to DS18

to determine if an intermittent condition exists.

No

• KEY OFF. A hard fault is present. GO to DS11

.

DS11 CHECK VOLTAGE BETWEEN VREF AND SIG RTN TO ACP SENSOR

• Disconnect ACP sensor.
• Key on, engine off.
• Measure voltage between VREF and SIG RTN circuits at the ACP sensor harness connector.

Is voltage between 4.0 and 6.0 volts?
Yes

• GO to DS12

.

No

• VREF is out of range. KEY OFF. GO to C1 See: C: Reference Voltage - Pinpoint Test

.

DS12 INDUCE OPPOSITE ACP SIGNAL

• Connect a jumper wire between ACP and VREF circuits at the ACP sensor harness connector.
• Key on, engine off.
• Access ACP V PID.

Note: If any scan tool communication concern occurs, remove jumper immediately and GO to DS13.
Is ACP V PID greater than 4.0 volts?
Yes

• REPLACE ACP sensor. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

No

• GO to DS13

.

DS13 CHECK ACP CIRCUIT FOR SHORT TO PWR GND OR SIG RTN IN HARNESS

• Key off.
• Disconnect scan tool from DLC.
• Disconnect PCM.
• Measure resistance between ACP and SIG RTN circuits at the ACP sensor harness connector.
• Measure resistance between the ACP circuit at the ACP sensor harness connector and the battery negative post.

Are both resistances greater than 10,000 ohms?
Yes

• GO to DS14

.

No

• REPAIR short circuit. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

DS14 CHECK ACP CIRCUIT FOR OPEN IN HARNESS

Note: Refer to the PCM connector pin numbers in the beginning of this Pinpoint Test.

• Measure resistance of ACP circuit between PCM harness connector pin and the ACP sensor harness connector.

Is resistance less than 5.0 ohms?
Yes

• GO to DS15

.

No

• REPAIR open ACP circuit. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

DS15 CHECK FOR THE A/C CLUTCH TO ENGAGE

• Reconnect ACP sensor.
• Key on, engine off.
• While listening for the A/C clutch to engage, turn the A/C on. Repeat if necessary.
• Key off.

Did the A/C clutch engage when the A/C was turned on?
Yes

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM). START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

No

• GO to DS16

.

DS16 VERIFY A/C SYSTEM HAS A REFRIGERANT CHARGE

• Restore vehicle.
• Verify that the A/C system has a refrigerant charge. (Refer to the Heating and Air Conditioning).

Does the A/C system have a refrigerant charge?
Yes

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM). START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

No

• REPAIR A/C system. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

DS18 CHECK FOR INTERMITTENT ACP CIRCUIT FAULT

• Key on, engine off.
• Access ACP V PID.
• Observe ACP V PID for an indication of a fault while completing the following (a fault will be indicated by a sudden change in ACP V PID voltage):
• Shake, wiggle, bend the ACP, SIG RTN and VREF circuits between the ACP sensor and the PCM.
• Lightly tap on the ACP sensor (to simulate road shock).

Is a fault indicated?
Yes

• ISOLATE fault and REPAIR as necessary. CLEAR the DTCs. START engine.

TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

No

• Unable to duplicate or identify fault at this time. GO to Z1 See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 5: Pinpoint Tests\Z: Intermittent - Pinpoint Test

.

DS20 DTC P1463: VERIFY A/C CLUTCH CAN DISENGAGE

• A/C and defroster off.
• Start engine.
• Verify that the A/C clutch disengages.

Is the A/C clutch disengaged?
Yes

• KEY OFF. GO to DS21

.

No

• GO to Section 3 See: Symptom Related Diagnostic Procedures, Symptom Chart 24 (A/C Compressor Runs Continuously, A/C Always On) to diagnose the always engaged A/C clutch.

DS21 CHECK FOR VOLTAGE AND GROUND TO A/C CLUTCH (USING NON POWERED TEST LAMP)

Note: If voltage and ground to A/C clutch has already been checked in the Section 3 See: Symptom Related Diagnostic Procedures, Symptom Charts, or the A/C clutch can be heard clicking on when the A/C is turned on, go to the question at the end of this test step.

• Disconnect A/C cycling switch. Install a jumper wire in the A/C cycling switch vehicle harness connector (to complete the circuit).
• Disconnect the A/C clutch.
• Connect a non-powered test lamp between the power pin and ground pin at the A/C clutch vehicle harness connector.
• Start engine.
• Turn A/C on, wait 15 seconds.
• Monitor test lamp.
• After testing turn key off, remove jumper and reconnect A/C clutch and A/C cycling switch.

Does test lamp light (or can A/C clutch be heard clicking on)?
Yes

• GO to DS22

.

No

• REFER to Heating and Air Conditioning.

DS22 CHECK IF A SUFFICIENT A/C PRESSURE CHANGE CAN BE DETECTED BY THE ACP PID

• Start engine.
• A/C off.
• Access ACP V PID.
• Note ACP V PID voltage.
• While monitoring ACP V PID voltage, turn A/C on. Five seconds after A/C clutch engagement, note voltage (if clutch does not engage, follow NO Action To Take).

Did the ACP V PID voltage change more than 0.3 volt within five seconds of clutch engagement?
Yes

• The ACP Sensor and PCM can detect a sufficient change in A/C system pressure.
• For Symptom without DTC P1463:
• RETURN to Section 3 See: Symptom Related Diagnostic Procedures.
• All others:
• REFER to Heating and Air Conditioning to check for proper operation of the A/C system. After any service. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

No

• KEY OFF, A/C off. GO to DS23

.

DS23 CHECK A/C SYSTEM PRESSURE AND PRESSURE CHANGE

• Install an A/C System Manifold Gauge Set and check the A/C system high pressure readings.
• Start engine.
• A/C off.
• Note the A/C high pressure reading.
• While monitoring the A/C system high pressure reading, turn the A/C on. Five seconds after clutch engagement, note the pressure (the pressure should increase).
• A/C off.

Did the A/C high pressure reading change more than 207 kPa (30 psi) within five seconds of clutch engagement?
Yes

• KEY OFF. GO to DS24

.

No

• A/C system pressure did not change as expected. REFER to Heating and Air Conditioning to check for proper mechanical operation of the A/C system. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

DS24 CHECK VOLTAGE BETWEEN VREF AND SIG RTN TO ACP SENSOR

• Disconnect ACP sensor.
• Key on, engine off.
• Measure voltage between VREF and SIG RTN circuits at the ACP sensor harness connector.

Is voltage between 4.0 and 6.0 volts?
Yes

• KEY OFF. GO to DS25

.

No

• VREF is out of range. KEY OFF. GO to C1 See: C: Reference Voltage - Pinpoint Test

.

DS25 CHECK ACP CIRCUIT FOR OPEN IN SENSOR

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

• Key off.
• ACP sensor disconnected.
• Disconnect PCM.
• Measure resistance of ACP circuit between PCM harness connector pin and the ACP sensor harness connector.

Is resistance less than 5.0 ohms?
Yes

• REPLACE ACP sensor. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.

No

• REPAIR open circuit. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Quick Test.