Defroster Doesn't Work on 01 Chevy?

If you smell antifreeze coming from the vents you likely have a leaking heater core. The heater core is the radiator that is on the inside to give you heat. If by not working you mean it blows hot air but does not clear the window then that would be normal for a leaky core. A leak creates steam. You cant defrost a window with steam. IT pretty much just makes it worse. To defrost you need dry air. In cars with AC they actually run the AC system to dry the air before they heat it and blow it on the window. In your case its being dried then picking up a bunch of slimy steam.

IF you mean that you dont get any air blowing out the DEF vents then in addition to your leaky core you have a door problem. Sort of above the heater outlets there is an electric motor with several arms on it that opens and closes doors to direct the air depending on what you have selected on the dial. Sometimes if something falls down the vents like a pencil it can jam the doors from moving properly. Sometimes the arms just pop off the motor so the doors cant move.

You will need to replace the heater core. The part is likely under $100 but you pretty much have to remove the entire dash out to get to it. This could easily be $500 in labor but does vary by model and year so its worth asking. A temporary patch assuming your system uses a normal looking radiator cap would be to remove the cap (when engine is cold) You will see that the cap has a rubber gasket on the cap part but then there is a plunger like smaller extension on the smaller part that also has a rubber gasket. What you want to do is remove part of this smaller inner gasket. Dont remove it all. What you are doing is preventing that inner part from sealing. This will prevent the system from getting pressurized with should make it leak slower. Once you fix it you will need a new cap but they are not that expensive. The system is normally under pressure because it raises the boiling point of the system. In winter high temps are usually not a problem. But you will for sure want to get it fixed before summer if it even lasts that long. If your cap does not have that inner plunger its one of the newer designs and there is not an easy way to keep the pressure out without leaking.

It sounds like your heater core is leaking, this would account for no heat and the smell of antifreeze. Check your coolent level it will also be low.