I have a 2000 v70 fwd and this winter we are having a serious problem with the brakes. It has happened a couple of times on mornings in the low 20's. My wife will drive to workout (10 mins each way) and then park the car for about an hour. When she jumps back in to head over to work there have been a couple of times that she steps on the brakes and NOTHING happens - it feels like there are breaks there but the car is not stopping?? There is no ice on the road. Brakes are strong and in good condition. Any thoughts or suggestions?

 

You're loosing your vacuum assist; brake booster is probably leaking causing water vapor to get inside the brake vacuum booster; this condenses into water which freezes below 32 degrees F; this causes the booster diaphragm to lock up and hence no brake assist..

at least that's what popped into my head when i read your symptoms...

In any case, ck your brake booster; could be something else in that system too like the check valve freezing or leaking when cold; the boost vac hose collapsing could also cause this...

Let us know what you find, but get it fixed asap, this is dangerous (esp with a woman driving it...)