Sweet Smell from AC in 2019 Honda Accord
A sweet smell coming from the AC vents typically indicates a coolant leak from the heater core. The sweet odor is characteristic of ethylene glycol-based antifreeze. This can lead to foggy windows, reduced heating performance, and potential engine overheating if the coolant level drops significantly.
Diagnosis Details
Possible Causes
Leaking heater core – Coolant escapes from the heater core into the HVAC case, producing a sweet smell when the AC or heat is on.
Coolant leak elsewhere (e.g., radiator, hoses, water pump) – Coolant may drip onto hot engine parts and be drawn into the cabin via the ventilation system.
Mold or mildew in the evaporator – While more musty than sweet, sometimes a sweetish odor can occur, but this is less common with a distinct sweet smell.
Related OBD-II Codes
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What You Should Do
Check the coolant level in the reservoir and under the hood for visible leaks.
Inspect the passenger floor area for dampness or a sticky residue.
If the heater core is leaking, it will need to be replaced, which is a labor-intensive job.
Also, have the AC system inspected for any refrigerant leaks (though refrigerant has a different smell).
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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.
