What are the symptoms of Unusual noise and metallic grinding when A/C is on in Audi S3?

No cold air from vents. Weak cabin cooling. Unusual noises when A/C is turned on. Warning light on dashboard

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Unusual noise and metallic grinding when A/C is on

Q: How to fix Unusual noise and metallic grinding when A/C is on in Audi S3?

Removal and replacement of the air conditioning compressor, replacement of the condenser with dryer, replacement of the expansion valve and thorough flushing of the entire refrigeration system before refilling.

in Audi S3 (2015-2015)

Symptoms

No cold air from vents
Weak cabin cooling
Unusual noises when A/C is turned on
Warning light on dashboard

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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

Refrigerant specifications for this model are available in the catalog.

Open refrigerant database

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