1998 Honda Civic Issues with air conditioning/heater

I was having trouble with my heater in the winter. Originally the heater had only been working on the high heat settings, which I assumed was a blown resistor. Eventually it stopped working entirely. I got it checked out, they replaced the resistor, everything seemed to be ok at first.

I noticed, however, that the heater/ac was now blowing out maybe half of what it used to. Also, every so often there is a noise that sounds a little bit like plastic shaking or blowing. About 4 months went by without a problem. A couple days ago the whole AC stopped working again. This time however, if I leave it running for about 5 minutes the AC will suddenly start working again. So I'm not sure if something is blown or what. Is something in there clogging it so even though it might be "technically working", nothing is coming out or is it something else?