I have never had an issue with Star-San and my Therminator. I do worry though, so I only use the Star-San in the chiller when it is hooked to the cleaning loop on my brewery (actually it is just hooked up to my lautering grant and pump combo and recirculates there). Otherwise, I stick that bad boy in my king-size pressure canner and fire it up after cleaning it. I have quit using Star-San on my brewing equipment (no need to sanitize that anyways), so the chiller only gets PBW or Oxy followed by a slight vinegar water rinse. Then nothing but tap water before everything is left to dry.
As for the AC coils... I would think it would be fine if you rinsed off before it set all day. Couple hours and a rinse should be fine once a year. The rest of the time I would just use a pressure hose and be careful not to bend the fins with the spray.
As for the AC coils... I would think it would be fine if you rinsed off before it set all day. Couple hours and a rinse should be fine once a year. The rest of the time I would just use a pressure hose and be careful not to bend the fins with the spray.