On Wednesday, July 15, 2020 at 7:03:32 PM UTC-4, Vic Smith wrote:

I assumed it was scale build up clogging it, but when I remove the old PVC I'll cut it up
and find out, and let you know. Now I have an excuse to do it.

I doubt it's scale, where would the lime come from? That should be distilled water hitting the pan.

I suspect it's dust off the coils combined with biological growth. In a constant wet environment all sorts of nasties can grow.