Engine compartment gas leak. Repair immediately.
**When this suddenly happened to us, my husband found that the oil filler cap had popped off. Luckily it was still under the hood, and as soon as he replaced it, the problem cleared up.
No, they do not. If you smell ammonia it is not coming from the heater unless something has been put inside the heater and is burning.
A burning smell from a car's brakes means that you are braking very hard or there is a electrical short circuit in the car. Another reason for a burning smell may actually be coming from the car's heater.
Because it is burning.
The burning rubber smell in the tranmisson breaking apart inside.
The belt is burning up and wind is pushing the smell through the air conditioning.
you probably have a bad heater core.
the heater core may be plugged up
The possible explanation for the smell may be that the heater core in the vehicle has a slight leak, therefore the smell of evaporating antifreeze will come through the vents until it is all dried up. Solution is to take the car to a garage and get the heater core replaced.
Leaking heater core
if you smell it inside, it's the heater core it has a leak.
you have a bad heater core in your vehicle
You might have a gas leak in your front engine compartment. The heater pull in air from the front and therefore if you got a gas leak it will pull the smell in get it check asap.