AC Not Cold and Bad Smell in Traffic
The AC cools on the highway but warms up in traffic, accompanied by a bad smell. This suggests a refrigerant issue (low charge or leak) combined with moisture or mold in the evaporator, or a failing condenser fan that reduces cooling at low speeds.
Diagnosis Details
Possible Causes
Low refrigerant charge due to a small leak, causing reduced cooling at idle when the compressor demand is highest.
Faulty condenser fan or fan relay, reducing airflow over the condenser in traffic, leading to high pressure and warm air.
Clogged or dirty evaporator core with mold/bacteria growth, causing bad smell and reduced cooling efficiency.
Failing A/C compressor clutch or expansion valve, causing intermittent cooling.
Related OBD-II Codes
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What You Should Do
Check refrigerant pressure with a gauge set; if low, inspect for leaks (dye test).
Test condenser fan operation at idle.
Clean or replace cabin air filter and treat evaporator with a disinfectant foam.
If smell persists, professional evaporator cleaning may be needed.
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.
