washer nozzle freezes

I know it's probably a general question, but I have a 93 Explorer. When it gets below or around 20 deg, the nozzles on my winshield washers freeze. Eventually as it heats up outside or go into a garage, they are fine. I've made sure that the washer revervoir is full & is clean. I've tried to clean the nozzle with a wire to no avail. Is there any way to keep them from freezing? I've had the truck now for 4 winters & this is the first time this has happened.

Are you using winterized windshield fluid? You can replace the nozzles and they are relatively cheap. If you do, replace both. They pop right out. Look at the new ones and you'll know what to do.