Intermittent Weak Airflow with Foul Odor from AC
The AC system in your 2020 Subaru Outback is producing weak airflow that comes and goes, along with a bad smell. This typically points to a clogged or dirty cabin air filter, a failing blower motor resistor, or mold/bacteria buildup in the evaporator case. The intermittent nature suggests an electrical or airflow restriction issue rather than a refrigerant leak.
Diagnosis Details
Possible Causes
Clogged cabin air filter restricting airflow and trapping moisture/debris causing odor
Failing blower motor resistor causing intermittent fan speed control
Mold or mildew growth on the evaporator coil due to lack of drainage or infrequent use
Blower motor motor brushes worn or debris in the fan cage
Refrigerant leak or low charge (less likely with intermittent airflow, but possible if compressor cycles)
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 airflow improves but still intermittent, test the blower motor resistor and blower motor for proper operation.
For the odor, use an AC evaporator cleaner foam to kill mold/bacteria.
If the issue persists, have a technician check the blower motor, resistor, and evaporator drain tube.
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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.
