No air in the cabin

Hi, so....long story short. I have a Fabia mk1 2004 with a 1.9 TDI. It had the resistance that controlled the air blown so it would work only in the 4th speed. I changed it at some point but, not being fully informed it blew after 2 days, as I realized afterwards because the cabin filter was done. So I said that I will change both of them, but didn't really do it. Was using it only in the 4th speed. Now....I don't normally use the AC in the summer as I drive with the open windows. But in the winter is quite handy (warm and clean windows). But I was heading on a long trip so I closed the windows and started the AC to the lowest temperature. The thing is that I never was sure about a little very stupid thing, and maybe you can help me, I have a button for AC, and it is usually green, if I press it, becomes orange, when it is orange, is it on or off? Back to story so I turned the speed to max and temperature to the lowest (i don't remember if the ac button was yellow or green) and it worked for a while (not doing that much of a good job, but it is an old car, and previous owners didn't take too much care of it, so i did not expect much of it) buuut, at some point, not long after I felt a burning smell and it died. Now I want it to fix before winter because foggy windows and here winters are quite cold, but I am not sure what is broken. Is it the blower itself or something else? how to inspect at home? and if it is the blower, I can't really find a new one....only used on ebay. Is there are the difference between blowers of Mk1 fabias with different engines? Should I even go for a used one?