AC Not Cold and Bad Smell in Traffic
The AC works well at highway speeds but blows warm air and produces a bad smell in stop-and-go traffic. This suggests a refrigerant issue or a failing component that only performs under higher engine RPMs.
Diagnosis Details
Possible Causes
Low refrigerant charge due to a slow leak (common in aging systems). At highway speeds, the compressor can still maintain some cooling, but at idle it cannot.
Faulty AC compressor clutch or compressor failure. The clutch may not engage properly at low RPMs, causing warm air in traffic.
Clogged or dirty evaporator core or cabin air filter, which can cause bad smell and reduced airflow, especially at low speeds.
Mold or mildew growth in the evaporator case (common cause of bad smell when AC is used).
Related OBD-II Codes
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What You Should Do
Have the AC system pressure tested and refrigerant level checked.
Inspect the compressor clutch operation at idle vs.
highway RPM.
Replace cabin air filter if dirty.
Consider an evaporator cleaning service if smell persists.
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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.
