What are the symptoms of Hissing from vents and slow loss of refrigerant in Audi A6 (C8)?

Unusual noises when A/C is turned on. Slow loss of refrigerant

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Hissing from vents and slow loss of refrigerant

Q: How to fix Hissing from vents and slow loss of refrigerant in Audi A6 (C8)?

Full disassembly of the dashboard and replacement of the evaporator. In Q5 (FY) models, precise installation of the SR3 bracket (fuse box) is crucial - an error during installation causes subsequent leakage of rainwater into the cabin. The manufacturer has issued a U43 warranty extension (10 years/100,000 miles) for selected models. Before expensive disassembly, check the gas detector at the vents - if the signal is positive with 0 UV dye under the hood = 100% evaporator.

in Audi A6 (C8) (2013-2025)

Symptoms

Unusual noises when A/C is turned on
Slow loss of refrigerant

DTC error codes

G395 low pressure

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Technical diagnosis (Premium)

Recognized technical fault:

Auxiliary controller voltage instability detected

Technical analysis

Detailed analysis of HVAC controller operation parameters, CAN bus data readings, and diagnostic signal waveforms. Purchase PRO access or log in to read the full fault analysis.

Confirmed solution

Complete step-by-step repair procedure including module non-volatile memory reset, sensor calibration, and correct wiring routing. Unlock the full report to see the instruction.

Parts needed

Filters ferrite anti-interference / noise suppressor
Auxiliary starting battery (depending on cell status)

Workshop hacks

Important workshop tips for mechanics regarding bypasses without expensive control module replacement and manufacturer software service bulletins.

TSB / TPI service bulletins

TSB-24-HVAC-01TPI-2068943/2

A/C Technical Specifications

(C8)

Refrigerant: R1234yf Amount (g): 500-550g Oil: PAG YF ISO 46 Oil (ml): 130 - 160ml

S6 (C8) - Najnowsza platforma C8 (4A)

Refrigerant: R1234yf Amount (g): 500 - 550g Oil: PAG46yf Oil (ml): 110 - 140ml

(4G/C7) kompresor Denso/Zexel

Refrigerant: R134a Amount (g): 570g Oil: PAG PAO 68 lub PAG ISO 46 Oil (ml): 120ml

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Hissing from vents and slow loss of refrigerant

Symptoms

DTC error codes

A/C Technical Specifications

Other problems in A6 (C8)

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