Sweet Smell from AC – Possible Coolant Leak
A sweet smell coming from the AC in a 2019 BMW 3 Series typically indicates a coolant leak, often from the heater core or a related hose. The sweet odor is characteristic of ethylene glycol in coolant. This can lead to engine overheating and interior fogging if not addressed promptly.
Diagnosis Details
Possible Causes
Heater core leak – Coolant escapes from the heater core into the cabin when the AC is on.
Coolant hose leak near the HVAC system – A small leak in a hose allows coolant to enter the air intake or evaporator area.
Evaporator drain clogged – Condensation mixed with coolant from a minor leak can produce a sweet smell.
Related OBD-II Codes
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What You Should Do
Check coolant level and look for visible leaks under the dashboard or near the heater core.
Inspect hoses connected to the HVAC system.
If coolant is low, top off and monitor.
Have a professional pressure test the cooling system and inspect the heater core.
Do not use the AC if the smell is strong, as coolant fumes can be harmful.
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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.
