Musty Smell from AC in 2020 Toyota RAV4
The musty odor when the AC is on is typically caused by moisture buildup in the evaporator core or cabin air filter, leading to mold or mildew growth. This is a common issue in humid climates and is not immediately dangerous but can affect air quality.
Diagnosis Details
Possible Causes
Clogged or dirty cabin air filter allowing mold/mildew to grow and recirculate musty odors.
Moisture accumulation on the AC evaporator core due to lack of drainage or infrequent use of the system, promoting microbial growth.
Debris or leaves trapped in the HVAC intake or blower motor area decomposing and producing odor.
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What You Should Do
Replace the cabin air filter first.
Then run the AC on high with fresh air for 10 minutes, then turn off AC but keep fan on high to dry the evaporator.
If odor persists, use an AC evaporator cleaner spray (foaming type) applied through the cabin air filter slot or drain tube.
Consider having a professional clean the evaporator coil if needed.
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Disclaimer: This AI-generated diagnosis is for informational reference only. Always consult a qualified mechanic for an in-person inspection. AutOwner is not responsible for decisions made based on this information.
