Refrigerant Pressure Sensor / Switch

A/C PRESSURE TRANSDUCER Before testing the A/C pressure transducer, be certain that the transducer wire harness connection is clean of corrosion and properly connected. For the A/C to operate, an A/C pressure transducer voltage reading between 0.451 and 4.519 volts is required. Voltages outside this range indicate a low or high refrigerant system pressure condition to the powertrain control module (PCM). The PCM is programmed to respond to a low or high refrigerant system pressure by suppressing operation of the A/C compressor. Refer to the A/C Pressure Transducer Voltage chart for the possible conditions indicated by the transducer voltage reading. The A/C pressure transducer is tested using a scan tool Testing and Inspection. A/C PRESSURE TRANSDUCER VOLTAGE

DESCRIPTION The A/C pressure transducer (1) sends a signal to the powertrain control module (PCM) which controls both A/C compressor clutch engagement/disengagement and electric cooling fan operation. The A/C pressure transducer is mounted on a fitting located on the A/C liquid line near the dash panel. The PCM will disengage the A/C compressor clutch when high side pressure rises above 2971 kPa (431 psi) or fall below 206 kPa (30 psi). The fitting for the A/C pressure transducer on the A/C liquid line is equipped with an O-ring seal and contains a Schrader-type valve to allow the transducer to be serviced without discharging the refrigerant system.

A/C PRESSURE TRANSDUCER Before testing the A/C pressure transducer, be certain that the transducer wire harness connection is clean of corrosion and properly connected. For the A/C to operate, an A/C pressure transducer voltage reading between 0.451 and 4.519 volts is required. Voltages outside this range indicate a low or high refrigerant system pressure condition to the powertrain control module (PCM). The PCM is programmed to respond to a low or high refrigerant system pressure by suppressing operation of the A/C compressor. Refer to the A/C Pressure Transducer Voltage chart for the possible conditions indicated by the transducer voltage reading. The A/C pressure transducer is tested using a scan tool Testing and Inspection. A/C PRESSURE TRANSDUCER VOLTAGE

DESCRIPTION The A/C pressure transducer (1) sends a signal to the powertrain control module (PCM) which controls both A/C compressor clutch engagement/disengagement and electric cooling fan operation. The A/C pressure transducer is mounted on a fitting located on the A/C liquid line near the dash panel. The PCM will disengage the A/C compressor clutch when high side pressure rises above 2971 kPa (431 psi) or fall below 206 kPa (30 psi). The fitting for the A/C pressure transducer on the A/C liquid line is equipped with an O-ring seal and contains a Schrader-type valve to allow the transducer to be serviced without discharging the refrigerant system.

The A/C pressure transducer (1) sends a signal to the powertrain control module (PCM) which controls both A/C compressor clutch engagement/disengagement and electric cooling fan operation. The A/C pressure transducer is mounted on a fitting located on the A/C liquid line near the dash panel. The PCM will disengage the A/C compressor clutch when high side pressure rises above 2971 kPa (431 psi) or fall below 206 kPa (30 psi).

The fitting for the A/C pressure transducer on the A/C liquid line is equipped with an O-ring seal and contains a Schrader-type valve to allow the transducer to be serviced without discharging the refrigerant system.

The A/C pressure transducer monitors the pressures in the high side of the refrigerant system through its

connection to a fitting on the A/C liquid line. The A/C pressure transducer will change its internal resistance in response to the pressures it monitors. The powertrain control module (PCM) or the engine control module (ECM) (depending on engine application) provides a five volt reference signal and a sensor ground to the A/C pressure transducer, then monitors the output voltage of the A/C pressure transducer on a sensor return circuit to determine refrigerant pressure. The PCM/ECM is programmed to respond to the A/C pressure transducer and other sensor inputs by controlling the operation of the A/C compressor clutch and the radiator cooling fan to help optimize A/C system performance and to protect the system components from damage. The PCM/ECM will disengage the A/C compressor clutch when high side pressure rises above 2971 kPa (431 psi) or fall below 206 kPa (30 psi). The A/C pressure transducer input to the PCM/ECM also prevents the A/C compressor clutch from engaging when ambient temperatures are below about 10° C (50° F) due to the pressure/temperature relationship of the refrigerant.

A Schrader-type valve in the A/C discharge line fitting permits the A/C pressure transducer to be removed or installed without disturbing the refrigerant in the A/C system.

The A/C pressure transducer is diagnosed using a scan tool (refer to HEATING & AIR CONDITIONING - ELECTRICAL DIAGNOSTICS article for more information).

The A/C pressure transducer cannot be adjusted or repaired and it must be replaced if found inoperative or damaged.

The A/C pressure transducer is tested using a scan tool (refer to HEATING & AIR CONDITIONING - ELECTRICAL DIAGNOSTICS article or appropriate Engine ELECTRICAL DIAGNOSTICS article for more information). Before testing the A/C pressure transducer, be certain that the transducer wire harness connection is clean of corrosion and properly connected. For the A/C to operate, an A/C pressure transducer voltage reading between 0.451 and 4.519 volts is required. Voltages outside this range indicate a low or high refrigerant system pressure condition to the powertrain control module (PCM). The PCM is programmed to respond to a low or high refrigerant system pressure by suppressing operation of the A/C compressor. Refer to the A/C PRESSURE TRANSDUCER VOLTAGE chart for the possible conditions indicated by the transducer voltage reading.

NOTE: It is not necessary to discharge the refrigerant system to replace the A/C pressure transducer.

NOTE: LHD model shown in illustration. RHD model similar.

1. Disconnect and isolate the negative battery cable. 2. Disconnect the wire harness connector (1) from the A/C pressure transducer (2) located on the A/C liquid line (3) near the dash panel (4) in the engine compartment. 3. Remove the A/C pressure transducer from the A/C liquid line and remove and discard the O-ring seal.

NOTE: Use only the specified O-ring as it is made of special material for R-134a. Use only refrigerant oil of the type required for the A/C compressor.

NOTE: LHD model shown in illustration. RHD model similar.

1. Lubricate a new rubber O-ring seal with clean refrigerant oil and install it onto the A/C pressure transducer fitting. 2. Install the A/C pressure transducer (2) onto the A/C liquid line (3) near the dash panel (4). Hand- tightened the transducer securely. 3. Connect the wire harness connector (1) to the A/C pressure transducer. 4. Reconnect the negative battery cable.

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The A/C pressure transducer (1) sends a signal to the powertrain control module (PCM) which controls both A/C compressor clutch engagement/disengagement and electric cooling fan operation. The A/C pressure transducer is mounted on a fitting located on the A/C liquid line near the dash panel. The PCM will disengage the A/C compressor clutch when high side pressure rises above 2971 kPa (431 psi) or fall below 206 kPa (30 psi).

The fitting for the A/C pressure transducer on the A/C liquid line is equipped with an O-ring seal and contains a Schrader-type valve to allow the transducer to be serviced without discharging the refrigerant system.

The A/C pressure transducer monitors the pressures in the high side of the refrigerant system through its

connection to a fitting on the A/C liquid line. The A/C pressure transducer will change its internal resistance in response to the pressures it monitors. The powertrain control module (PCM) or the engine control module (ECM) (depending on engine application) provides a five volt reference signal and a sensor ground to the A/C pressure transducer, then monitors the output voltage of the A/C pressure transducer on a sensor return circuit to determine refrigerant pressure. The PCM/ECM is programmed to respond to the A/C pressure transducer and other sensor inputs by controlling the operation of the A/C compressor clutch and the radiator cooling fan to help optimize A/C system performance and to protect the system components from damage. The PCM/ECM will disengage the A/C compressor clutch when high side pressure rises above 2971 kPa (431 psi) or fall below 206 kPa (30 psi). The A/C pressure transducer input to the PCM/ECM also prevents the A/C compressor clutch from engaging when ambient temperatures are below about 10° C (50° F) due to the pressure/temperature relationship of the refrigerant.

A Schrader-type valve in the A/C discharge line fitting permits the A/C pressure transducer to be removed or installed without disturbing the refrigerant in the A/C system.

The A/C pressure transducer is diagnosed using a scan tool (refer to HEATING & AIR CONDITIONING - ELECTRICAL DIAGNOSTICS article for more information).

The A/C pressure transducer cannot be adjusted or repaired and it must be replaced if found inoperative or damaged.

The A/C pressure transducer is tested using a scan tool (refer to HEATING & AIR CONDITIONING - ELECTRICAL DIAGNOSTICS article or appropriate Engine ELECTRICAL DIAGNOSTICS article for more information). Before testing the A/C pressure transducer, be certain that the transducer wire harness connection is clean of corrosion and properly connected. For the A/C to operate, an A/C pressure transducer voltage reading between 0.451 and 4.519 volts is required. Voltages outside this range indicate a low or high refrigerant system pressure condition to the powertrain control module (PCM). The PCM is programmed to respond to a low or high refrigerant system pressure by suppressing operation of the A/C compressor. Refer to the A/C PRESSURE TRANSDUCER VOLTAGE chart for the possible conditions indicated by the transducer voltage reading.

NOTE: It is not necessary to discharge the refrigerant system to replace the A/C pressure transducer.

NOTE: LHD model shown in illustration. RHD model similar.

1. Disconnect and isolate the negative battery cable. 2. Disconnect the wire harness connector (1) from the A/C pressure transducer (2) located on the A/C liquid line (3) near the dash panel (4) in the engine compartment. 3. Remove the A/C pressure transducer from the A/C liquid line and remove and discard the O-ring seal.

NOTE: Use only the specified O-ring as it is made of special material for R-134a. Use only refrigerant oil of the type required for the A/C compressor.

NOTE: LHD model shown in illustration. RHD model similar.

1. Lubricate a new rubber O-ring seal with clean refrigerant oil and install it onto the A/C pressure transducer fitting. 2. Install the A/C pressure transducer (2) onto the A/C liquid line (3) near the dash panel (4). Hand- tightened the transducer securely. 3. Connect the wire harness connector (1) to the A/C pressure transducer. 4. Reconnect the negative battery cable.

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