Can An Air Conditioner Blow Out Dust?

I have an old air conditioner in my apartment, probably 10+ years old. I thought of replacing it, took it out, but then changed my mind and put it back in. However, I'm pretty sure I didn't put it in right. So my question is, can an in-wall air conditioner belch out dust? Might be a placebo effect but I just need some reassurance (from here of all places).