What are the symptoms of A/C cooling is weak and gradually loses performance in BMW E90?

Weak cabin cooling. Problem visible at standstill or in traffic. Problem appears while driving

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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 BMW E90?

Replacing the electric radiator fan (Auxiliary Fan). Check the fan plug for pin corrosion before replacing the entire module.

in BMW E90 (2005-2018)

Symptoms

Weak cabin cooling
Problem visible at standstill or in traffic
Problem appears while driving

DTC error codes

DME: Electric fan, activation

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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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A/C cooling is weak and gradually loses performance

Symptoms

DTC error codes

A/C Technical Specifications

Other problems in E90

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