It’s gotten cold here in St Louis, however, the temperature has warmed up enough to thaw the drain pipes. Originally, the black tank valve was frozen, and would not budge. Since it’s warmed up constantly for a few day’s, the valve opens freely. However, it’s not draining. I have tank heaters, and poured everywhere antifreeze in the tank. Honestly, I’m not sure whilst gently pulling the valve whilst frozen, if it did open slightly. I’m not sure if the tank slowly drained. The tank level lights are not accurate. Any suggestions??