I have a GE french door refrigerator that quit dispensing water. I disconnected the main water line to see if it was clogged and it's not. When I unscrew the filter, it pops off like it's under a lot of pressure. Thinking possibly a line is froze u on the door. I ran some weedeater line up the dispensing tube, but that didn't help. How do you unthaw a frozen line, other than unplugging the unit.