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Unpleasant odor (musty/mold) and fogging of windows in the cabin

Q: What are the symptoms of Unpleasant odor (musty/mold) and fogging of windows in the cabin in Mazda 626?

Musty mold odor from vents. Fogging windows

Q: How to fix Unpleasant odor (musty/mold) and fogging of windows in the cabin in Mazda 626?

Mechanical unblocking of the condensate drain channels (evaporator drain) and the windshield, replacing the cabin filter, and then carrying out the evaporator drying procedure (full heating in a closed circuit with A/C turned off for 15 minutes) and applying the original encapsulating coating 'Mazda Air Cooling Coil Coating' using a special gun.

in Mazda 626 (1998-2026)

Symptoms

Musty mold odor from vents
Fogging windows

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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

Standard

Refrigerant: R134a Amount (g): 625 –700g Oil: GU10 PAO 68 lub PAG ISO 46 Oil (ml): 150ml

Standard

Refrigerant: R134a Amount (g): 700g Oil: GU10 PAO 68 lub PAG ISO 46 Oil (ml): 175ml

Standard

Refrigerant: R134a Amount (g): 750 – 800g Oil: ATMOS 150 PAO 68 Oil (ml): 150ml

See full specification

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