Sweet Smell from AC in 2019 Hyundai Elantra
A sweet smell coming from the AC vents typically indicates a coolant leak from the heater core. The heater core uses engine coolant (antifreeze), which has a sweet odor. When the AC is on, moisture can mix with leaked coolant and produce the smell through the vents.
Diagnosis Details
Possible Causes
Heater core leak – Coolant is leaking from the heater core inside the dashboard, and the AC system blows the sweet-smelling vapor into the cabin.
Coolant leak elsewhere (e.g., hose or radiator) – Coolant may be dripping onto hot engine parts and being drawn into the cabin air intake.
AC evaporator drain clogged – Moisture buildup can sometimes produce a sweet, musty smell, but this is less common than a coolant leak.
Related OBD-II Codes
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What You Should Do
Check coolant level in the reservoir.
If low, inspect for visible leaks under the dashboard (passenger side floor) or under the hood.
Have a mechanic perform a pressure test on the cooling system and inspect the heater core.
If the heater core is leaking, it will need replacement, which is a labor-intensive job.
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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.
