The DU Lounge

We have an odd arrangement where our garage is in the basement. The rest ov the basement is finished like a 3rd floor.
But, because of that the "basement wall" is exposed to the elements and it's just concrete. When we had the walls put in, the guy ran the water from the washing machine behind the wall, so when it gets really cold, no house heat gets to the pipes.
What I've done that works is to find some area of the pipe that's easy to get to and put a blow dryer blowing on the pipe.
Copper & water are both really good conductors of heat, so the heat gets to the frozen spor
T and starts to melt it.
You only need a pin hole of flow because then just running the water brings in new mass that isn't close to the freezing point. The heat of the 45° or so water melts the rest of the ice.
If you're getting a little flow, the line has to have a tiny space for water to leak through, also meaning the whole line isn't frozen solid. If it was, the pressure downstream of the plug would be zero.
Try the hairdryer thing. Worked for me.