I have had one line of my 3 lines fail to blow air. It was due to water getting back into the line from seeping past the diffuser. I cycled the aeration on and off daily with a timer. This must have allowed a stuck open check valve to allow water to fill the line. I pulled the diffuser, unhooked it, and at least a gallon of water ran out, maybe two. I have not had that problem since and it has been well over a year.
What diffusers are you running?
Are you sure it's ice?
And, answers to the above questions may help the forum focus in on a definitive problem/solution.
