Smoke Or Mist From The Air Vents
Smoke from the vents with a burning smell points to an electrical fault, while a sweet-smelling mist and a greasy film on the windscreen point to a leaking heater core.
Critical risk
Stop if it smells of burning. Coolant mist also needs prompt attention because it means coolant loss.
Short answer · Why is smoke coming from my air vents?
Burning smoke from the vents usually comes from the blower motor or its resistor overheating. A sweet mist that fogs the windscreen is coolant from a leaking heater core. A short burst of white mist when the AC starts in humid weather can be normal condensation and has no smell.
Safe checks you can do
- Smell the smokeBurning: electrical. Sweet: coolant. No smell: condensation.If it smells burnt, stop, switch off and get out.
- Check the coolant level when coldA drop supports a heater core leak.
- Look at the windscreenA greasy film supports coolant mist.
Questions that narrow it down
- Does it smell sweet?Heater core leak.
- Does it smell burnt?Electrical fault.
- Is it only when the AC starts?Possibly normal condensation.
Possible causes
Listed without ranking. Use the questions above to see which ones fit your car.
- Blower motor or resistor overheatingBurning smell.
- Leaking heater coreSweet mist and foggy glass.
- Condensation from the ACBrief, odourless mist.
- Debris burning in the heater boxLeaves on a hot part.
Questions about Smoke Or Mist From The Air Vents
Is coolant mist harmful?
Breathing coolant vapour is not healthy; ventilate and have it fixed.
Is AC mist normal?
A brief, odourless mist in humid weather can be normal.