To eliminate unpleasant smells from your vents when using the heater or AC, start by changing or cleaning the air filter, as a dirty filter can trap odors. Next, ensure your ducts are clean and free of mold or debris by having them professionally inspected and cleaned if necessary. Additionally, check for any leaks or standing water in the system, as these can contribute to musty smells. Regular maintenance and using air fresheners specifically designed for HVAC systems can also help keep the air fresh.
bad heater core bad heater core
heater core
you need a new heater core
Generally, with that smell- the heater core has gone bad.
Most of the time it is caused by a hole in the heater core, do you smell a sweet smell? The sweet smell would be the antifreeze.
your heater core is leaking anitfreeze! heatercoreleaks antifreeze into the heater & ac vents causing a burnt spell & oily film on the front window.
If there is the smell of anti-freeze, you're almost sure to be replacing the heater core.See "Related Questions" below for more
More than likely the heater core is leaking.
You have either a cracked heater core or bad heater hoses that are allowing antifreeze to enter into the vehicle............
A sweet smell indicates engine coolant. It you can't see any leaking from the hoses in the engine compartment, it's probably the heater core. With the smell coming from the vents too, it's most likely the heater core, but rule out easy fixes first.
smoky mist coming from the heater vents.
The most common signs of a heater core problem is either leaking antifreeze or a mist coming from the air vents. There will also be a sickly sweet smell in most cases.