Audi compressor won’t engage

Diagnose and fix Audi compressor won’t engage

Audi has issued a service bulletin #15-69 (2020124/13) to address an Audi AC compressor won’t engage on the vehicles listed below. In addition to an Audi compressor won’t engage, you may also find the following trouble codes:

DTC 00457 – Vehicle Electrical System Control Module – J519 .
DTC 00256 – A/C Pressure/temperature Sensor -G395 – Incorrect Signal
DTC 00256 – A/C Pressure/temperature Sensor -G395- No signal/communication
DTC 00457 – Vehicle Electrical System Control Module -J519- Please check DTC
DTC 00256 – A/C Pressure/temperature Sensor -G395- Incorrect Signal
DTC 01592 – Air Quality Sensor -G238- No signal/communication
DTC 00256 – A/C Pressure/temperature Sensor -G395- No signal/communication

Audi compressor won’t engage affected by service bulletin #15-69 (2020124/13)

A4 2009-2012 VIN range 000001 – 999999
A4 2013 VIN range N000001 – N045670
A4 2013 VIN range A000001 – A231729
A5 2008-2012 VIN range 000001 – 999999
A5 2013 VIN range 000001 – 071355
S5 / RS 5 2013 VIN range 900000 – 902787
A5 Cabriolet 2010-2012 VIN range 000001 – 999999
A5 Cabriolet 2013 VIN range 000001 – 015616
S5 Cabriolet / RS5 Cabriolet 2013 VIN range 900000 – 900501
A6 2005-2012 VIN range 000001 – 999999
A6 2013 VIN range 000001 – 134357
A7 2012 VIN range 000001 – 999999
A7 2013 VIN range 000001 – 134357
A8 2004-2012 VIN range 000001 – 999999
A8 2013 VIN range 000001 – 029602
Q5 2009 – 2012 000001 – 999999
Q5 2013 VIN range 000001 – 083307

Audi AC compressor won’t engage symptoms

The Audi service bulletin describes a condition where the AC compressor clutch won’t engage but the HVAC blower will blow normally when you turn on the AC. You’ll get airflow but no cold air. You may also find a discharged battery.

Audi has discovered that the A/C pressure/temperature sensor G395 leaks refrigerant, causing it to show an incorrect or implausible value. It’s the leak and low refrigerant level in the system that prevents the AC compressor clutch from engaging.

In addition, Audi has found that the LIN cable connecting the vehicle electrical system control module, J519, to sensor G395 may be pinched or cut. This particular problem affects the A4/S4, A5/S5 Coupe and Cabriolet, and Q5 vehicles. But the A6 and A8 are not affected by this type of failure.

The battery dies because pressure sensor G395/G65 sends an incorrect signal that keeps the digital bus busy, prevent the computers from going into sleep mode.

Fix for Audi compressor won’t engage

Audi has issued an updated pressure sensor that solves the problem. Start your diagnosis by checking for a refrigerant leak at the G395 pressure sensor. If you find a leak, replace the sensor with the updated part. If the refrigerant pressures are good and you find no leak, pursue normal diagnostics.

4H0959126A Pressure sensor 1
7H0820896 O-ring

Next, check the LIN cable connecting the vehicle electrical system control module to sensor for cuts or chaffing. Also, check the wire terminals in the connector at sensor G395 for proper attachment or possible corrosion, and for any pins that may be pushed back or widened.
©, 2019 Rick Muscoplat