What are the symptoms of A/C cooling is weak and gradually loses performance in Audi S4 B9?

No cold air from vents. Weak cabin cooling

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A/C cooling is weak and gradually loses performance

Q: How to fix A/C cooling is weak and gradually loses performance in Audi S4 B9?

Physical replacement of the air conditioning condenser with a reinforced part from a newer production line and performing a leak test and filling the system.

in Audi S4 B9 (2017-2018)

Symptoms

No cold air from vents
Weak cabin cooling

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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

kompresor Zexel/Denso

Refrigerant: R134a Amount (g): 600g Oil: PAG PAG 46 lub PAO 68 Oil (ml): 150ml

See full specification

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