Intermittent Weak AC Airflow with Bad Odor
The AC system in your 2019 Nissan Altima has intermittent weak airflow and a bad smell, which often points to a clogged or dirty cabin air filter, evaporator core issues, or a failing blower motor resistor. The odor suggests mold or bacteria buildup in the evaporator case.
Diagnosis Details
Possible Causes
Clogged or dirty cabin air filter restricting airflow and trapping moisture/mold
Evaporator core covered in mold/bacteria due to lack of drainage or infrequent use
Failing blower motor resistor causing intermittent fan speed issues
Debris or leaf buildup in the HVAC intake or evaporator case
Related OBD-II Codes
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What You Should Do
Start by replacing the cabin air filter (located behind the glove box).
If the odor persists, use an AC evaporator cleaner spray (foam type) to kill mold.
Check blower motor operation at all speeds; if intermittent, test/replace the blower motor resistor.
Ensure the evaporator drain tube is not clogged.
Related Repairs
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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.
