AC Not Working - Help!
12-25-2017, 03:11 PM
#1
AudiWorld Junior Member
Thread Starter
AC Not Working - Help!
Hi,
Have been trying to fix AC for a long time. Have been to mechanic but still not sorted.
Heres what I know / have done so far:
1. AC does not cool - appears compress ore is not activating because no noticable change in engine load when toggling AC switch on dash.
2. Climate control module is reporting two faults:
Have been trying to fix AC for a long time. Have been to mechanic but still not sorted.
Heres what I know / have done so far:
1. AC does not cool - appears compress ore is not activating because no noticable change in engine load when toggling AC switch on dash.
2. Climate control module is reporting two faults:
- 00256 - A/C Pressure/Temperature Sensor (G395) 008 - Implausible signal
- 00457 - Control Module for Network (J519) 013 - Check DTC Memory
3. J519 is reporting:- 00256 - A/C Pressure/Temperature Sensor (G395) 004 - No Signal/Communication
4. Enabling the output test for the J519 compressor control valve causes the AC compressor to activate -engine load changes and air gets colder.
5. Replaced G395 sensor (twice to ensure faulty replacement part was not the cause). Did not resolve the faults.
6. Checked signal at G395 connector - +12V, GND and LIN signal were present (measured LIN signal with an oscilloscope and could see digital waveform but unsure if this orginates from the J519 module or another sensor on the bus). Unsure if +12V is correct voltage.
7. Soldered wires direct to sensor terminals (to eliminate a faulty connector) - did not resolve the faults.
8. Having found http://uberlame.com/a6_tsb/HVAC/Air%...02020124-2.pdf I tested continuity of LIN wire back to J519 (using colour code) - seems ok. Ran a LIN wire from sensor direct to J519 to wire position - did not resolve the faults.
Any further ideas of what to try? Banging my head on the wall with this now....
- 00457 - Control Module for Network (J519) 013 - Check DTC Memory
3. J519 is reporting:- 00256 - A/C Pressure/Temperature Sensor (G395) 004 - No Signal/Communication
4. Enabling the output test for the J519 compressor control valve causes the AC compressor to activate -engine load changes and air gets colder.
5. Replaced G395 sensor (twice to ensure faulty replacement part was not the cause). Did not resolve the faults.
6. Checked signal at G395 connector - +12V, GND and LIN signal were present (measured LIN signal with an oscilloscope and could see digital waveform but unsure if this orginates from the J519 module or another sensor on the bus). Unsure if +12V is correct voltage.
7. Soldered wires direct to sensor terminals (to eliminate a faulty connector) - did not resolve the faults.
8. Having found http://uberlame.com/a6_tsb/HVAC/Air%...02020124-2.pdf I tested continuity of LIN wire back to J519 (using colour code) - seems ok. Ran a LIN wire from sensor direct to J519 to wire position - did not resolve the faults.
Any further ideas of what to try? Banging my head on the wall with this now....
12-26-2017, 01:10 PM
#3
AudiWorld Junior Member
Thread Starter
Which AC pressure gauges? Don;t know how to read them. Have had a mechanic put external gauges on and pressure was said to be fine. What's more as per my original post I can active the compressor via VCDS and it cools. Note that these models do not have a clutch and the comprssor turns full time,. instead they have a control valve only controlling effective compressor effort.
01-19-2018, 11:58 AM
#6
AudiWorld Junior Member
Thread Starter
So I finally got this sorted.
As it turns out, two of the receptacle pins in the G395 sensor connector had pushed back.
Looking at the connector it was hard to see this because of the rubber seals around each wire.
I removed the pins, squeezed them to make a tighter fit on the sensor pin and pushed them back all the way into place and the fault code dissappeared.
I cannot understand how previously soldering the wires direct to the sensor did not work (tried this twice) but all sorted now.
Now I just have the problem that the AC is too weak to keep the car cool on a hot day when it has been sitting in the sun. No fault codes are reported so I assume a re-gas would sort this??
As it turns out, two of the receptacle pins in the G395 sensor connector had pushed back.
Looking at the connector it was hard to see this because of the rubber seals around each wire.
I removed the pins, squeezed them to make a tighter fit on the sensor pin and pushed them back all the way into place and the fault code dissappeared.
I cannot understand how previously soldering the wires direct to the sensor did not work (tried this twice) but all sorted now.
Now I just have the problem that the AC is too weak to keep the car cool on a hot day when it has been sitting in the sun. No fault codes are reported so I assume a re-gas would sort this??
01-23-2018, 04:35 AM
#7
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Which AC pressure gauges? Don;t know how to read them. Have had a mechanic put external gauges on and pressure was said to be fine. What's more as per my original post I can active the compressor via VCDS and it cools. Note that these models do not have a clutch and the comprssor turns full time,. instead they have a control valve only controlling effective compressor effort.
How did you get the compressor to run via VCDS?
Pls tell me the procedure.
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01-26-2018, 04:42 PM
#8
AudiWorld Junior Member
Thread Starter
1. Select control module
2. Select central elec module
3. Select Output tests.
4. Select AC compressor and press start
01-26-2018, 04:43 PM
#9
AudiWorld Junior Member
Thread Starter
So I finally got this sorted.
As it turns out, two of the receptacle pins in the G395 sensor connector had pushed back.
Looking at the connector it was hard to see this because of the rubber seals around each wire.
I removed the pins, squeezed them to make a tighter fit on the sensor pin and pushed them back all the way into place and the fault code dissappeared.
I cannot understand how previously soldering the wires direct to the sensor did not work (tried this twice) but all sorted now.
Now I just have the problem that the AC is too weak to keep the car cool on a hot day when it has been sitting in the sun. No fault codes are reported so I assume a re-gas would sort this??
As it turns out, two of the receptacle pins in the G395 sensor connector had pushed back.
Looking at the connector it was hard to see this because of the rubber seals around each wire.
I removed the pins, squeezed them to make a tighter fit on the sensor pin and pushed them back all the way into place and the fault code dissappeared.
I cannot understand how previously soldering the wires direct to the sensor did not work (tried this twice) but all sorted now.
Now I just have the problem that the AC is too weak to keep the car cool on a hot day when it has been sitting in the sun. No fault codes are reported so I assume a re-gas would sort this??