A/C Pressure/Temperature Sensors

Sensor for Connection with Valve on Refrigerant Circuit

NOTE:

Switching pressures, removing and installing switches as well as switch arrangement and version. Refer to Refrigerant Circuit (vehicle-specific Service Information).

There are different versions of this sensor with different functions and with different names. For example, the following illustrated A/C Pressure/Temperature Sensor -G395- is installed on a Golf GTE Audi A4, Audi Q5, and Audi Q5 hybrid. Refer to SYSTEM OVERVIEW - REFRIGERANT CIRCUIT, R1234YF .

Fig 1: A/C Temp/Pressure Sensor G65 / G395

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Before loosening the sensor threaded connection, check the version. Refer to SYSTEM OVERVIEW - REFRIGERANT CIRCUIT, R1234YF .

On a sensor for a connection on the refrigerant circuit without a valve. The refrigerant must be extracted before loosening the threaded connection. If the sensor is not removed within 10 minutes after extraction, pressure may build up in refrigerant circuit due to evaporation. Extract the refrigerant again.

There are various designations, depending on the function and the vehicle. Refer to SYSTEM OVERVIEW - REFRIGERANT CIRCUIT, R1234YF .

• The A/C pressure/temperature sensor is installed for example instead of the high pressure sensor or the refrigerant circuit pressure sensor. Refer to Refrigerant Circuit (vehicle-specific Service Information).
• The A/C pressure/temperature sensor, the refrigerant circuit pressure sensor and the high pressure sensor are available in different versions. Currently the sensor's only exterior difference is the parts number. Therefore, make sure that the part numbers are correctly allocated when replacing them (part number - Parts Information). Reason: these sensors produce different signals that can only be evaluated by the respective control modules. Use the Vehicle Diagnostic Tester "Guided Fault Finding"  function for the A/C system or refer to Refrigerant Circuit (vehicle-specific Service Information).
• When voltage is applied, the A/C pressure/temperature sensor (and the refrigerant circuit pressure sensor exchange information via the data bus (for example via the "LIN Bus") with the corresponding control module. The respective control module uses this information to calculate the pressure (and temperature) in the refrigerant circuit and any faults detected are reported to the control module. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.
• The A/C pressure/temperature sensor transmits the measured value for the refrigerant circuit pressure and the measured temperature to the connected control module. The refrigerant circuit pressure sensor only transmits the measured value for the refrigerant circuit pressure to the connected control module. Even if only the pressure signal is evaluated on most vehicles, no other pressure sensor is or will be installed on a vehicle in which a A/C pressure/temperature sensor is designed. Refer to the Parts Information.
• The temperature measured by the A/C pressure/temperature sensor differs from the actual refrigerant temperature in the refrigerant circuit because of the sensor version and its component location. Therefore it is not currently evaluated by all control modules and is not used to regulate the A/C system. Refer to SYSTEM OVERVIEW - REFRIGERANT CIRCUIT, R1234YF (vehicle-specific Service Information).
• With this information the corresponding control modules calculate the refrigerant circuit pressure and activates the downstream control modules (radiator fan control module, engine control module etc.) via the data bus. These control modules then active for example the A/C Clutch -N25-, the radiator fan and the engine. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding"  for the A/C system and refer to Refrigerant Circuit (vehicle-specific Service Information).

Sensor for Connection without Valve on Refrigerant Circuit

Possible Names for This Sensor

Fig 2: A/C Temp/Pressure Sensor G395 -- G826 -- G827

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

• A/C Pressure/Temperature Sensor -G395- (for example on e-Golf and Audi Q7 e-tron)
• A/C Pressure/Temperature Sensor 2 -G826- (for example on Audi Q7 e-tron)
• A/C Pressure/Temperature Sensor 3 -G827- (for example on Audi Q7 e-tron)

There are different versions of this sensor -A-. Depending on the version, they physically only differ in part number, or with the stamped label -B- when the part number is the same. Pay attention to the correct allocation, part number, and label when replacing. Refer to the Parts Information and SYSTEM OVERVIEW - REFRIGERANT CIRCUIT, R1234YF .

These sensors exchange information with the respective control module via the data bus (for example via the "LIN bus") when voltage is applied. The respective control module uses this information to calculate the pressure (and temperature) in the refrigerant circuit and any faults detected are reported to the control module. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.

With this information the respective control module calculates the refrigerant circuit pressure and activates the downstream control module or components (radiator fan control module, pumps, valves etc.) via the data bus according to the specifications. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function and refer to SYSTEM OVERVIEW - REFRIGERANT CIRCUIT, R1234YF (vehicle-specific Service Information).