Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSAUDI2009A6 BASEREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 39 (HEATING & AIR CONDITIONING)87 AIR CONDITIONINGA/C REFRIGERANT SYSTEM, TESTINGIDENTIFYING MALFUNCTIONS IF SPECIFIED VALUES ARE NOT OBTAINEDNOTES

2009 Audi A6 Base

Identifying malfunctions if specified values are not obtained: Notes

2009 Audi A6 BaseSECTION Notes

WARNING: This page does not describe the selected car, but rather 17 other vehicles, including the 2009 Audi S4, 2009 Audi A4, 2008 Audi S4, 2008 Audi RS 4, and 2008 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

In "Reading measuring value block" function → Read Measuring Value Block (function 08) , select display group "001". Repeat cooling output test → A/C refrigerant system, testing . During cooling output test, observe display in zones "1" and "4". Activation for A/C Compressor Regulator Valve N280 deactivated during cooling output test (drop in control current to below 0.55 A)?
↓ Yes ↓	↓ No ↓
check DTC memory → Diagnostic Trouble Code (DTC) Memory, checking (function 02) , eliminate faults displayed and erase DTC memory → Diagnostic Trouble Code (DTC) Memory, erasing (function 05) .	Increase in pressure in refrigerant circuit (display zone "4") during cooling output test?
Read measuring value block, display group "002" (compressor shutoff criteria) and eliminate cause of shutoff.	↓ Yes ↓	↓ No ↓
Repeat cooling output test.	↓ Test continued (increase in pressure in refrigerant circuit) Continuation of test - Pressure in refrigerant circuit increases	Fault in refrigerant circuit * See note.

* If applicable, check again that compressor is actually being driven. On vehicles with 8-cyl. engine, the drive shaft may have become removed from the compressor drive unit for example → Compressor drive unit, checking, replacing

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.