This morning when my daughter tried to use the bathroom upstairs cold water would not run from the sink and the shower would not run at all. The toilet flushes and hot water runs in that sink. The other sinks, showers and toilets are also functioning normally. It is winter and it is cold but the pipe freezing scenario does not make sense. Any ideas?

Hi Ktgould...

The shower wouldn't run because it is probably PRESSURE BALANCED which means that if cold water or hot water isn't running then the hot or cold water will also not run and the shower valve would appear as if both hot and cold was down.

With that being said, for you to have two fixtures (sink and shower) that have no cold water then I have to first guess that you do indeed have a frozen pipe. Here, you would use a hair dryer to heat the cold water pipe under the sink and see if that thawed things out. While heating the cold water pipe be sure to keep the cold water faucet wide open and the shower valve open to the warm setting so you will know when the pipe(s) thaw.

Also, just in case there is a broken pipe as a result of the freeze, you better know where the main water shutoff is... just in case it needs to be shut real fast!

Also note here, that you may need to drop the trim plate off the front of the shower valve so you can stick the nose of the hair dryer in behind the wall and heat that space to finish the job (again, shower valve is 1/2 way open).

Use common sense and don't heat behind the wall for too long without double checking that you aren't burning something... ;)

Let me know what you think so far, OK?

Mark