Hi everyone.
After searching and not finding anything like what I am experiencing, here it is.

If I put the heater on, it smells like hot coolant inside of the car.
However, I am not loosing coolant. The reservoir is just at the same level it has sat since the beginning of the summer.

Can anybody shed some light?
I am ready to go at the heater (either by myself or going to a mechanic, but this is pretty strange.

Thanks for your help.

 

You probably have a slight heater-core leak. That's the way they almost always start - little or no noticeable coolant loss, just the odor of coolant (the warm heater core evaporates the coolant before it can accumulate anywhere). The core will start to leak at the joint between the core itself and the end-caps. When it gets bad enough, you will start getting coolant slime condensing on the windows. The next step will be noticeable coolant loss, and possible coolant puddles in the cabin.

 

Check the underside of the carpet on the passenger floorboard, if it's wet then your heater core is leaking.

Ask me how I know...

 

Mines doing the same thing, its most likely the heater core. Mines not puddling yet and replacing mine asap before it does.