The lowest place in the line is underneath the pump house where the sun never shines.

I could probably thaw it out with a salamander heater but it's a lot easier to just wait on the weather.

We're supposed to have another cold snap over the next couple days then start warming up.
We're looking at upper 40s next week with nighttime lows well above freezing.
I've got a feeling the problem is going to fix itself.