plastic burning smell and now no heat from AC - HELP?

Exactly, on my 1995 Caprice Classic, the heater does not generate no heat anymore after a ride with my wife, when we smelled a plastic burn like odor...
You do not want your wife in the car on such moments....
Heat set at maximum will only generate somewhat warm air from the motor compartment to get into the cabin, clearly not from the AC/heater.
Is there a heater element in the dash to be replaced or so?
Unfortunately I am not a mechanic, so I am in the blue here.
Anybody there to offer help....pleeeeeeease?
Thank you in advance!

The heater core is accessed from under the passenger's side of the dash. It has a hidden screw along the firewall.

Are you losing coolant? If not it may be the heater core is clogged. You can try a reverse flush to get the gunk out. You may have to do it more than once. The smell of plastic can be plastic, or coolant. You can check for loss through the core by looking at the condensate drain at the firewall. It is under the evaporator and there should be a small rubber elbow on it. If there is coolant coming from the drain, the heater core has a hole in it. The heater core is not terribly expensive, but is a bit of a pain to replace. You can get them from Rock Auto, and they will ship to Europe. Find their post in the vendor section, and you can get a 5% discount on the part.

If the core is bad, then you need to replace it. To remove the condensate tray you need a 5.5mm socket and a variety of extensions, especially to access the hidden screw. The core is held in by a couple of bolts/screws/nuts, and my guess is that they are 10mm heads. You must also remove the hoses from the core on the engine bay side.

Hello Fred,
Thank you for your explanation and support!
It seems I will have to take a dive into it!
Will keep you posted on result!