I brewed a Yuengling clone on Sunday, its now Thursday. I not only have no airlock activity (not unexpected), but I have no visible krausen. Is it normal for there to be absolutely no signs for a lager? I pitched at about 65 but it got rather cold during the night and my lagerator is in my uninsulated garage. The thermometer on the fridge read 47 degrees and the carboy thermometer read just above 50 degrees. Did I crash the yeast?