How to fix Musty/mouldy smell in the cabin in BMW 328i (E90)?

An effective solution involves manually removing the cabin filter, and in many cases also dismantling the blower motor itself, to insert a tube and directly pour professional chemical foam (e.g. Kool-It, Nextzett Klima-Clean) into the evaporator core. High operational repeatability. Ozonation is ineffective - the chemicals must wash the evaporator directly.

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Musty/mouldy smell in the cabin

in BMW 328i (E90) (2006-2022)

Symptoms

Musty mold odor from vents

DTC error codes

Brak

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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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